Glossary of Healthcare Terms and Definitions

A

ABG (Arterial Blood Gas) – A test that measures the acidity (pH) and levels of oxygen and carbon dioxide in the blood from an artery.

Abrasion – A wound caused by superficial damage to the skin, no deeper than the epidermis.

Abscess – A confined pocket of pus that collects in tissues, organs, or spaces inside the body.

Ablation – The removal of a body part, biological function, or growth, often by surgery, chemicals, or heat.

ABO Blood Group System – The classification of human blood based on the presence or absence of antigens A and B on the surface of red blood cells.

Abruptio Placentae – A condition where the placenta detaches from the uterine wall before childbirth.

Absorption – The process by which the body takes in or absorbs nutrients, medications, etc., through tissues like the skin or intestinal lining.

Acetabulum – The socket of the hipbone, into which the head of the femur fits.

Acidosis – A condition characterized by excessive acid in the body fluids.

Acne – A skin condition characterized by red pimples, often due to inflamed or infected sebaceous glands.

Acoustic Neuroma – A benign tumor on the main nerve leading from the inner ear to the brain.

Acquired Immunodeficiency Syndrome (AIDS) – A chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV).

Acromegaly – A hormonal disorder that develops when the pituitary gland produces too much growth hormone during adulthood.

ACTH (Adrenocorticotropic Hormone) – A hormone produced by the pituitary gland that stimulates the adrenal glands.

Acupuncture – A form of alternative medicine in which thin needles are inserted into the body.

Acute – A condition that comes on quickly and can cause severe symptoms, but typically lasts only a short time.

Adenectomy – Surgical removal of a gland.

Adenocarcinoma – A type of cancer that forms in mucus-secreting glands throughout the body.

Adenoidectomy – Surgical removal of the adenoids, small lymphoid tissues located at the back of the throat.

Adenoma – A benign tumor formed from glandular structures in epithelial tissue.

Adhesion – Bands of scar-like tissue that form between two surfaces inside the body, causing them to stick together.

Adipose Tissue – Body tissue containing stored fat.

Adjustment Disorder – A group of symptoms, such as stress, feeling sad or hopeless, and physical symptoms that can occur after you go through a stressful life event.

Adjuvant Therapy – Additional cancer treatment given after the primary treatment to lower the risk that the cancer will come back.

Adrenal Gland – A small gland located on top of the kidney that produces hormones that regulate metabolism, immune system, blood pressure, response to stress, and other essential functions.

Adrenaline (Epinephrine) – A hormone secreted by the adrenal glands that increases rates of blood circulation, breathing, and carbohydrate metabolism and prepares muscles for exertion.

Adverse Effect – An undesired harmful effect resulting from a medication or other intervention.

Aerobic Exercise – Any activity that uses large muscle groups, can be maintained continuously, and is rhythmic in nature.

Aerophagia – Swallowing air, usually due to rapid eating or nervousness, leading to belching and discomfort.

Afebrile – Not having a fever.

Afferent Nerve – A nerve that carries sensory information toward the central nervous system.

AFP (Alpha-fetoprotein) – A plasma protein produced by the fetus, elevated levels of which can indicate certain pathologies in pregnant women and liver disease.

Aftercare – Care and support provided after hospitalization or a medical procedure.

Agglutination – The clumping of particles, often used in reference to blood cells in testing or in immune responses.

Aging – The process of becoming older, a biological progression that is associated with physical, psychological, and social changes.

Agnosia – The inability to process sensory information. Often there is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss.

Agoraphobia – An anxiety disorder characterized by an intense fear of being in places where escape might be difficult.

AIDS (Acquired Immunodeficiency Syndrome) – See #12.

Airway Obstruction – Any obstruction of the air passages, either partial or complete.

Albinism – A group of genetic disorders characterized by little or no melanin production.

Albumin – A simple form of protein that is soluble in water and coagulable by heat, such as that found in egg white, blood serum, and milk.

Alcoholism – An addiction to the consumption of alcoholic liquor or the mental illness and compulsive behavior resulting from alcohol dependency.

Alkalosis – A condition resulting from a balance in the body leading to an increased alkalinity (pH) in the blood and body tissues.

Allergen – A substance that can cause an allergic reaction.

Allergy – A condition in which the immune system reacts abnormally to a foreign substance.

Alopecia – Hair loss from the scalp or elsewhere on the body.

Alpha Blocker – A type of medication that is used to treat high blood pressure and urinary retention associated with benign prostatic hyperplasia.

ALS (Amyotrophic Lateral Sclerosis) – Also known as Lou Gehrig’s disease, it is a specific disease that causes the death of neurons controlling voluntary muscles.

Alternate Care Facility – A facility that is temporary and provides care due to an emergency or disaster.

Alzheimer’s Disease – A progressive neurologic disorder that causes the brain to shrink and brain cells to die.

---

B

Bacteremia – The presence of bacteria in the bloodstream, often associated with severe infections.

Bacterial Vaginosis – A condition in women where the normal balance of bacteria in the vagina is disrupted and replaced by an overgrowth of certain bacteria.

Barium – A silvery-white metallic element used in radiographic imaging to enhance the visibility of internal structures during X-rays.

Basal Cell Carcinoma – The most common form of skin cancer that arises from the basal cells of the skin and hair follicles.

Basal Metabolic Rate (BMR) – The rate at which the body uses energy while at rest to maintain vital functions such as breathing and keeping warm.

Bell’s Palsy – A condition that causes a temporary weakness or paralysis of the muscles in the face.

Benign – A term used to describe a condition, tumor, or growth that is not cancerous and does not spread to other parts of the body.

Beta Blockers – A class of medications that are primarily used to manage abnormal heart rhythms and to protect the heart from a second heart attack.

Bile – A fluid produced by the liver that helps digest fats.

Bile Ducts – Tubes that carry bile from the liver to the gallbladder and from the gallbladder to the small intestine.

Bilirubin – A yellow compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates.

Biopsy – A diagnostic procedure that involves collecting a small sample of tissue for laboratory examination.

Bipolar Disorder – A mental disorder marked by extreme shifts in mood from high (manic) to low (depressive) and vice versa.

Birth Asphyxia – A condition resulting from a lack of oxygen to the brain or body that occurs during the birth process.

Bladder – A hollow organ in the lower abdomen that stores urine from the kidneys before it is discharged from the body.

Blepharoplasty – A surgical procedure to correct deformities, defects, or disfigurations of the eyelids; and it is often used cosmetically to modify eye appearance.

Blood Pressure – The pressure of the blood within the arteries, related to the force and rate of the heartbeat and the diameter and elasticity of the arterial walls.

Bone Marrow – The soft, spongy tissue that lies within the hollow interior of long bones, which produces blood cells.

Bone Density – A measure of the amount of minerals (mostly calcium and phosphorous) contained in a certain volume of bone.

Bradycardia – An abnormally slow heart rate, typically defined as a heart rate less than 60 beats per minute.

Bradypnea – Abnormally slow breathing rates.

Bronchitis – Inflammation of the lining of the bronchial tubes, which carry air to and from the lungs.

Bronchoscopy – A procedure that allows a doctor to examine the inside of the lungs, including the bronchi.

Bruxism – The involuntary or habitual grinding of the teeth, typically during sleep.

Buccal – Pertaining to or directed towards the cheek.

Bulimia Nervosa – An eating disorder characterized by episodes of binge eating followed by behaviors such as vomiting to avoid gaining weight.

Bundle Branch Block – A condition in which there’s a delay or obstruction along the pathway that electrical impulses travel to make your heart beat.

Bunion – A bony bump that forms on the joint at the base of the big toe.

Bursitis – Inflammation of a bursa, typically one in the knee, elbow or shoulder.

Bypass Surgery – Surgical procedure to create a new pathway for blood flow to bypass a blocked artery.

Basal Insulin – Insulin that is effective for keeping blood glucose levels stable during periods of fasting (such as overnight).

Beta Cells – Cells that make insulin, a hormone that controls the level of glucose in the blood.

Biocompatibility – The ability of a material to perform with an appropriate host response in a specific situation.

Bioinformatics – The science of collecting and analyzing complex biological data such as genetic codes.

Biomarker – A biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease.

Biomechanics – The study of the structure and function of biological systems such as humans, animals, plants, organs, and cells by means of the methods of mechanics.

Biosynthesis – The production of complex molecules within living organisms or cells.

Bioterrorism – The use of biological agents, such as pathogens or toxins, as weapons to inflict harm or death to humans, animals, or plants.

Biparietal Diameter – A measurement of the fetal head used in ultrasonography to estimate gestational age and fetal growth.

Blastocyst – A stage of embryonic development that is characterized by a fluid-filled cavity and a cluster of cells from which the embryo develops.

Blind Study – A type of clinical trial in which the participants do not know whether they are receiving the active treatment or a placebo.

Blood Culture – A test that checks for foreign invaders like bacteria or yeast in the blood.

Blood Glucose Monitoring – The ongoing measurement of blood sugar (glucose) levels.

Blood Transfusion – The process of transferring blood or blood products into one’s circulation intravenously.

BMI (Body Mass Index) – A measure used to classify an individual’s body weight relative to height.

Botulism – A rare but serious illness caused by a toxin that attacks the body’s nerves, leading to difficulty breathing, muscle paralysis, and even death.

Brachytherapy – A form of radiotherapy where a sealed radiation source is placed inside or next to the area requiring treatment.

Brainstem – The central trunk of the brain, continuing downward to form the spinal cord.

Breast Biopsy – A procedure in which a small sample of breast tissue is removed and examined to check for breast cancer.

Bronchiolitis – A common lung infection in young children and infants that causes inflammation and congestion in the small airways (bronchioles) of the lung.

---

C

Cachexia – Extreme weight loss and muscle wasting seen in patients with severe chronic illnesses such as cancer and AIDS.

Caldwell-Luc Procedure – A surgical operation on the cheek sinuses to remove infections and promote drainage.

Calcaneus – The large bone forming the heel.

Calcification – The process in which calcium builds up in body tissue, causing the tissue to harden.

Calcitonin – A hormone secreted by the thyroid that lowers blood calcium levels.

Candidiasis – A fungal infection caused by yeasts that belong to the genus Candida.

Cannulation – The insertion of a cannula into a body cavity, duct, or vessel.

Capillary – The smallest of a body’s blood vessels that make up the microcirculation.

Carbapenem-Resistant Enterobacteriaceae (CRE) – A family of bacteria that are difficult to treat because they have high levels of resistance to antibiotics.

Carcinogen – Any substance that promotes the formation of cancer.

Carcinoma – A type of cancer that starts in cells that make up the skin or the tissue lining organs, such as the liver or kidneys.

Cardiomegaly – An enlargement of the heart, often due to high blood pressure or coronary artery disease.

Cardiomyopathy – A disease of the heart muscle that makes it harder for the heart to pump blood to the rest of the body.

Cardiopulmonary Resuscitation (CPR) – Emergency procedure that combines chest compressions often with artificial ventilation in an effort to manually preserve intact brain function until further measures are taken to restore spontaneous blood circulation and breathing in a person who is in cardiac arrest.

Carotid Endarterectomy – A surgical procedure used to reduce the risk of stroke, by correcting stenosis (narrowing) in the common carotid artery or internal carotid artery.

Carpal Tunnel Syndrome – A condition caused by compression of the median nerve as it travels through the wrist at the carpal tunnel and causes pain, numbness, and tingling.

Cataract – Clouding of the lens of the eye which leads to a decrease in vision.

Catheter – A tube that can be inserted into a body cavity, duct, or vessel to allow drainage, administration of fluids or gases, or access by surgical instruments.

Cauterization – A medical procedure used to burn a part of a body to remove or close off a part of it.

Celiac Disease – An immune reaction to eating gluten, a protein found in wheat, barley, and rye.

Cellulitis – A common and potentially serious bacterial skin infection.

Central Nervous System (CNS) – The part of the nervous system consisting of the brain and spinal cord.

Cephalic – Pertaining to the head.

Cerebral Palsy – A group of permanent movement disorders that appear in early childhood.

Cerebrospinal Fluid (CSF) – A clear fluid found in the brain and spinal cord.

Cervical – Pertaining to the cervix or to the neck region.

Chemotherapy – A type of cancer treatment that uses one or more anti-cancer drugs as part of a standardized chemotherapy regimen.

Chiropractic – A form of alternative medicine concerned with the diagnosis and treatment of mechanical disorders of the musculoskeletal system, especially the spine.

Cholecystectomy – Surgical removal of the gallbladder.

Cholelithiasis – The presence of gallstones in the gallbladder.

Cholesterol – A type of fat, or lipid, which is produced by the liver and found in the blood.

Chondromalacia – A condition where the cartilage on the undersurface of the patella (kneecap) deteriorates and softens.

Chronic – Long-standing, persistent, opposite of acute.

Cirrhosis – Severe scarring of the liver and poor liver function seen at the terminal stages of chronic liver disease.

Clavicle – Collarbone, a long bone that serves as a strut between the shoulder blade and the sternum or breastbone.

Cleft Lip – A congenital split in the upper lip on one or both sides of the center, due to a failure of fusion of the maxillary and medial nasal processes (formation of the primary palate).

Clinical Trial – A research study that tests how well new medical approaches work in people.

Cloning – The process of creating a copy of a biological entity (gene, organism, or cell).

Clostridium Difficile (C. diff) – Bacterial infection, primarily associated with antibiotic use, causing severe diarrhea and other intestinal disease.

Coagulation – The action or process of a liquid, especially blood, changing to a solid or semi-solid state.

Cognitive Behavioral Therapy (CBT) – A form of psychotherapy that treats problems and boosts happiness by modifying dysfunctional emotions, behaviors, and thoughts.

Colitis – Inflammation of the inner lining of the colon.

Collagen – The main structural protein found in skin and other connective tissues, widely used in purified form for cosmetic surgical treatments.

Colonoscopy – An exam used to detect changes or abnormalities in the large intestine (colon) and rectum.

Colostomy – A surgical procedure that brings one end of the large intestine out through the abdominal wall.

Coma – A state of deep unconsciousness that lasts for a prolonged or indefinite period, caused especially by severe injury or illness.

Computed Tomography (CT) – A diagnostic imaging test used to create detailed images of internal organs, bones, soft tissue, and blood vessels.

Concussion – A type of traumatic brain injury caused by a blow to the head or body, a fall, or another injury that jars or shakes the brain inside the skull.

Congenital – (Of a disease or physical abnormality) present from birth.

Contraception – The deliberate use of artificial methods or other techniques to prevent pregnancy as a consequence of sexual intercourse.

---

D

Dacryocystitis – Inflammation of the lacrimal sac, primarily due to infection.

Debridement – The medical removal of dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue.

Decubitus Ulcer – Also known as a pressure ulcer or bedsore, caused by prolonged pressure on the skin.

Deep Vein Thrombosis (DVT) – A blood clot in a deep vein, usually in the legs.

Dehydration – A condition that results when the body loses more water than it takes in.

Dementia – A broad category of brain diseases that cause a long-term and often gradual decrease in the ability to think and remember.

Dental Caries – Decay and crumbling of a tooth or teeth.

Dermatitis – Inflammation of the skin.

Dermatome – An area of skin that is mainly supplied by a single spinal nerve.

Detoxification – The process of removing toxic substances or qualities.

Diabetes Mellitus – A metabolic disorder characterized by high blood sugar, insulin resistance, and relative lack of insulin.

Diabetic Ketoacidosis – A serious diabetes complication where the body produces excess blood acids (ketones).

Diagnosis – The identification of the nature and cause of an illness.

Dialysis – A procedure to remove waste products and excess fluid from the blood when the kidneys stop working properly.

Diaphragm – The main muscle of respiration, located beneath the lungs.

Diarrhea – The condition of having at least three loose or liquid bowel movements each day.

Dietitian – An expert on diet and nutrition.

Differentiation – The process by which cells or tissues undergo a change toward a more specialized form or function.

Diffuse – Spread out over a large area; not concentrated.

Digestion – The process by which the body breaks down food into absorbable substances.

Digital Rectal Exam (DRE) – An exam of the lower rectum the doctor performs with a gloved, lubricated finger.

Dilatation – The action or condition of becoming or being made wider, larger, or more open.

Diplopia – Double vision.

Dislocation – Displacement of one or more bones at a joint.

Diuretic – A substance that promotes the production of urine.

Diverticulitis – Inflammation or infection of one or more diverticula in the digestive tract.

DNA (Deoxyribonucleic Acid) – A molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms.

Dopamine – A type of neurotransmitter that is involved in many functions, including memory, sleep, mood, pleasurable reward, behavior, and cognition.

Dorsal – Pertaining to the back or posterior of a structure.

Dosage – The size or frequency of a dose of a medicine or drug.

Down Syndrome – A genetic chromosome 21 disorder causing developmental and intellectual delays.

Drainage – The removal of fluids from a body part.

Dressings – Materials used to protect and heal wounds.

Droplet Transmission – Transmission of infection by droplets produced when an infected person coughs or sneezes.

Drug Interaction – A situation in which a substance affects the activity of a drug when both are administered together.

Drug Resistance – The reduction in effectiveness of a drug such as an antimicrobial or an antineoplastic in curing a disease or condition.

Dry Socket – A painful dental condition that can occur after the removal of a permanent adult tooth.

Duodenum – The first section of the small intestine immediately beyond the stomach.

Dupuytren’s Contracture – A fixed flexion contracture of the hand where the fingers bend towards the palm and cannot be fully extended.

Dysarthria – A motor speech disorder resulting from neurological injury.

Dyskinesia – Distortion or impairment of voluntary movement.

Dysmenorrhea – Painful cramps that occur during menstruation.

Dysphagia – Difficulty or discomfort in swallowing.

Dysplasia – The presence of cells of an abnormal type within a tissue, which may signify a stage preceding the development of cancer.

Dyspnea – Difficult or labored breathing.

Dystonia – A movement disorder in which a person’s muscles contract uncontrollably.

Dysuria – Painful or difficult urination.

---

E

Echocardiogram – A sonogram of the heart used primarily to measure heart function.

Eclampsia – A severe complication of pregnancy characterized by the onset of seizures, usually in a patient who has developed pre-eclampsia.

Ectopic Pregnancy – A pregnancy in which the fetus develops outside the womb, typically in a fallopian tube.

Edema – Swelling caused by excess fluid trapped in the body’s tissues.

EEG (Electroencephalogram) – A test used to find abnormalities related to electrical activity of the brain.

Efferent Nerve – A nerve that carries signals away from the central nervous system toward the limbs and organs.

Ejection Fraction – The percentage of blood that is pumped out of a filled ventricle with each heartbeat.

Elbow Dislocation – Occurs when the bones of the forearm move out of place compared to the bone of the upper arm.

Electrocardiogram (ECG) – A test that records the electrical activity of the heart.

Electrolyte – Minerals in the blood and other body fluids that carry an electric charge.

Electromyography (EMG) – A diagnostic procedure to assess the health of muscles and the nerve cells that control them.

Embolism – The lodging of an embolus, a blockage-causing piece of material, inside a blood vessel.

Emesis – The action or process of vomiting.

Encephalitis – Inflammation of the brain, often due to infection.

Endarterectomy – Surgical removal of part of the inner lining of an artery.

Endocrinology – The branch of physiology and medicine concerned with endocrine glands and hormones.

Endometrial Biopsy – A procedure to take a small sample of the lining of the uterus.

Endometriosis – A disorder in which tissue similar to the tissue that normally lines the inside of the uterus grows outside the uterus.

Endoscopy – A procedure in which an instrument is introduced into the body to give a view of its internal parts.

Endotracheal Intubation – A medical procedure in which a tube is placed into the windpipe through the mouth or nose.

Enema – The injection of fluid into the lower bowel by way of the rectum.

Enteritis – Inflammation of the intestine, especially the small intestine, usually accompanied by diarrhea.

Enzyme – A protein that catalyzes chemical reactions of other substances without being destroyed or altered upon completion of the reactions.

Epidemic – A widespread occurrence of an infectious disease in a community at a particular time.

Epidermis – The outer layer of cells covering an organism.

Epidural – An epidural anesthesia, a method of anesthesia that blocks pain in a particular region of the body.

Epiglottis – A flap of cartilage at the root of the tongue, which is depressed during swallowing to cover the opening of the windpipe.

Epilepsy – A disorder in which nerve cell activity in the brain is disturbed, causing seizures.

Episiotomy – A surgical cut made at the opening of the vagina during childbirth, to aid a difficult delivery and prevent rupture of tissues.

Erythrocyte – A red blood cell that is typically a biconcave disc without a nucleus.

Escharotomy – A surgical procedure that cuts away dead tissue from a burn, to relieve tension and pressure from swelling, which can restore blood flow.

Esophagitis – Inflammation of the lining of the esophagus.

Esophagus – The part of the alimentary canal that connects the throat to the stomach.

Essential Tremor – A nervous system (neurological) disorder that causes involuntary and rhythmic shaking.

Estrogen – Any of a group of steroid hormones that promote the development and maintenance of female characteristics of the body.

Euthanasia – The painless killing of a patient suffering from an incurable and painful disease or in an irreversible coma.

Exacerbation – An increase in the severity of a disease or its symptoms.

Excision – The act of cutting out; surgical removal.

Exfoliation – The process of removing dead skin cells from the outer layer of your skin.

Exostosis – A benign growth on a bone.

Expectorant – A medicine that promotes the secretion of sputum by the air passages, used to treat coughs.

Extracorporeal – Occurring or situated outside the body.

Extracorporeal Membrane Oxygenation (ECMO) – A procedure that uses a machine to take over the work of the lungs and sometimes the heart.

Extrapyramidal Symptoms – Side effects such as involuntary movement and muscle stiffness, caused by certain medications.

Exudate – Fluid, such as pus or clear fluid, that leaks out of blood vessels into nearby tissues.

Eye Strain – Discomfort when looking at something for a long time, such as a computer screen.

Erythema – Redness of the skin caused by capillary dilation.

Ectasia – Dilation or distension of a tubular structure.

Exanthem – A widespread rash usually occurring in children.

Excretion – The process of eliminating or expelling waste matter.

Extension – An anatomical movement that increases the angle between parts of the body, such as straightening a flexed limb.

External Fixation – A surgical treatment used to stabilize bone and soft tissues at a distance from the operative or injury focus.

Extravasation – The leakage of intravenously (IV) infused potentially damaging medications into the extravascular tissue around the site of infusion.

Erythropoietin – A hormone produced by the kidney that promotes the formation of red blood cells by the bone marrow.

---

F

---

G

---

H

Habituation – A decrease in response to a stimulus after repeated presentations.

Hallucination – A perception in the absence of external stimulus that has qualities of real perception.

Halo Brace – A brace used to immobilize the head and neck.

Hamstring – Any of three muscles at the back of the thigh that function to flex and rotate the leg and extend the thigh.

Hand, Foot, and Mouth Disease – A contagious illness caused by different viruses.

Hapten – A small molecule that, when combined with a larger carrier such as a protein, can elicit an immune response.

HDL (High-Density Lipoprotein) – Often referred to as “good” cholesterol because it helps remove other forms of cholesterol from your bloodstream.

Heart Block – A disease in the electrical system of the heart that controls the rate and rhythm of the heartbeats.

Heart Failure – A condition in which the heart is unable to pump sufficiently to maintain blood flow to meet the body’s needs.

Hematocrit – The ratio of the volume of red blood cells to the total volume of blood.

Hematoma – A solid swelling of clotted blood within the tissues.

Hematuria – The presence of blood in urine.

Hemiparesis – Weakness on one side of the body.

Hemiplegia – Paralysis on one side of the body.

Hemodialysis – A procedure where a dialysis machine and a special filter called an artificial kidney, or a dialyzer, are used to clean the blood.

Hemoglobin – A protein in red blood cells that carries oxygen.

Hemolysis – The destruction of red blood cells.

Hemophilia – A disorder in which blood doesn’t clot normally.

Hemorrhage – Excessive or profuse bleeding.

Hemorrhoid – Swollen and inflamed veins in the rectum and anus that cause discomfort and bleeding.

Hepatectomy – The surgical removal of all or part of the liver.

Hepatic – Relating to or affecting the liver.

Hepatitis – Inflammation of the liver, usually caused by viral infections.

Hepatomegaly – Enlargement of the liver.

Hernia – A condition in which part of an organ is displaced and protrudes through the wall of the cavity containing it.

Herpes – A group of viral diseases causing herpetic sores.

Heterozygous – Having two different alleles of a particular gene or genes.

Hiatal Hernia – A type of hernia in which abdominal organs (typically the stomach) slip through the diaphragm into the middle compartment of the chest.

Hiccups – Involuntary contractions of the diaphragm followed by a rapid closure of the vocal cords.

High-Intensity Interval Training (HIIT) – A form of cardiovascular exercise that involves short intervals of extremely intense activity alternated with longer intervals of less intense activity.

Hippocampus – A major component of the brains of humans and other vertebrates, involved in memory forming, organizing, and storing.

Histamine – A compound that is released by cells in response to injury and in allergic and inflammatory reactions, causing contraction of smooth muscle and dilation of capillaries.

Histology – The study of the microscopic structure of tissues.

HIV (Human Immunodeficiency Virus) – The virus that causes AIDS.

Holistic Medicine – A form of healing that considers the whole person — body, mind, spirit, and emotions — in the quest for optimal health and wellness.

Homeostasis – The tendency toward a relatively stable equilibrium between interdependent elements, especially as maintained by physiological processes.

Hormone – A regulatory substance produced in an organism and transported in tissue fluids such as blood to stimulate specific cells or tissues into action.

Hormone Replacement Therapy (HRT) – Treatment to relieve symptoms of menopause by replacing estrogen hormone.

Hospice – A type of care and a philosophy of care that focuses on the palliation of a chronically ill, terminally ill, or seriously ill patient’s pain and symptoms.

Host – An organism that harbors a parasitic, a mutualistic, or a commensalist guest (symbiont), the guest typically being provided with nourishment and shelter.

Human Genome – The complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria.

Hydration – Maintenance of body fluid balance.

Hydrocephalus – A condition in which fluid accumulates in the brain, typically in young children, enlarging the head and sometimes causing brain damage.

Hydrotherapy – The use of water for pain relief and treatment.

Hydroxyzine – An antihistamine used to treat itching caused by allergies.

Hyperbaric Oxygen Therapy – A treatment that involves breathing pure oxygen in a pressurized room or tube.

Hyperglycemia – An excess of glucose in the bloodstream, often associated with diabetes mellitus.

Hyperplasia – An increase in the number of cells in an organ or tissue, which may lead to the enlargement of the part or structure.

Hypertension – High blood pressure, a chronic medical condition in which the blood pressure in the arteries is elevated.

Hyperthyroidism – The production of too much thyroxine hormone, accelerating the body’s metabolism significantly.

---

I

Iatrogenic – Conditions or responses resulting from medical treatment or advice itself.

Ibuprofen – A nonsteroidal anti-inflammatory drug (NSAID) commonly used to reduce fever, pain, and inflammation.

Ileostomy – A surgical opening constructed by bringing the end of the small intestine (the ileum) out onto the surface of the skin.

Ileum – The third and final part of the small intestine.

Imaging – Techniques and processes used to create images of the human body for clinical purposes or medical science.

Immobilization – The act of rendering a body part motionless, often to aid recovery.

Immune Response – The body’s defensive reaction to foreign substances or organisms.

Immune System – The bodily system that protects the body from foreign substances, cells, and tissues.

Immunization – The process by which a person or animal becomes protected against a disease.

Immunodeficiency – When the immune system’s ability to fight infectious disease is compromised or entirely absent.

Immunoglobulins – A class of proteins that function as antibodies produced by the immune system in response to foreign substances.

Immunosuppression – Reduced activation or efficacy of the immune system.

Impaction – A condition where stool becomes hard and stuck in the intestines.

Implant – A medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure.

Impotence – The inability to achieve or maintain an erection of the penis during sexual performance.

In Vitro – Performed or taking place in a test tube, culture dish, or elsewhere outside a living organism.

In Vivo – Performed or taking place in a living organism.

Incontinence – Lack of voluntary control over urination or defecation.

Incubation Period – The period between exposure to an infection and the appearance of the first symptoms.

Induction – The process or action of bringing about or giving rise to something.

Infarction – Tissue death (necrosis) caused by an interruption in the supply of blood to a part of the body.

Infection – The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body.

Inflammation – A localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful, especially as a reaction to injury or infection.

Influenza – A highly contagious viral infection of the respiratory passages causing fever and severe aching.

Ingestion – The consumption of a substance by an organism.

Inhalation – The act of breathing in; the intake of air or other substances into the lungs.

Inherited – A genetic condition or trait passed down from one or both parents to a child, at conception.

Injection – The act of administering a liquid, especially a drug, into a person’s body using a needle and syringe.

Injury – Harm or damage that is done or sustained.

Inpatient – A patient who stays in a hospital while under treatment.

Insomnia – Difficulty in falling asleep or staying asleep.

Insulin – A hormone produced in the pancreas by the islets of Langerhans, which regulates the amount of glucose in the blood.

Intensive Care Unit (ICU) – A special department of a hospital or health care facility that provides intensive treatment medicine.

Interferon – A group of signaling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, and also tumor cells.

Intermittent Claudication – Pain in the leg muscles that occurs during exercise and is relieved by rest.

Internal Medicine – A medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases.

Intervention – The act of intervening, interfering or interceding with the intent of modifying the outcome.

Intestine – The digestive tube from stomach to anus, consisting of the small intestine and the large intestine.

Intubation – The insertion of a tube into an external or internal orifice of the body for the purpose of adding or draining fluid or air, used especially to allow breathing when it is not possible in a natural way.

Intravenous (IV) – Administered within or into a vein.

Invasive Procedure – A procedure involving entry into the living body (as by incision or by insertion of an instrument).

Iodine – A chemical element necessary for normal growth and development.

Irradiation – Exposure to radiation of wavelengths shorter than those of visible light (e.g., X-rays, ultraviolet light).

Irritable Bowel Syndrome (IBS) – An intestinal disorder causing pain in the belly, gas, diarrhea, and constipation.

Ischemia – An inadequate blood supply to an organ or part of the body, especially the heart muscles.

Isolation – The process or fact of isolating or being isolated, often to contain the spread of something considered dangerous, especially in the context of infectious disease.

Isotope – Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei.

IVF (In Vitro Fertilization) – A process of fertilization where an egg is combined with sperm outside the body.

Iliac Crest – The upper border of the iliac bones, which form the prominence of the pelvis.

Ilium – The large broad bone forming the upper part of each half of the pelvis.

---

J

Jaundice – A condition characterized by yellowing of the skin and the whites of the eyes, caused by elevated bilirubin levels.

Jejunum – The part of the small intestine between the duodenum and ileum.

Joint – A structure in the human or animal body at which two parts of the skeleton are fitted together.

Jugular Vein – Veins in the neck that return blood from the head to the heart.

Juvenile Diabetes – Another term for Type 1 Diabetes, a chronic condition in which the pancreas produces little or no insulin.

Juvenile Rheumatoid Arthritis – A type of arthritis that occurs in children ages 16 or younger, causing inflammation and stiffness of joints.

Jackson-Pratt Drain – A hollow bulb-like device used to collect drainage from surgical sites.

Jaw – The lower part of the face that moves when an animal opens its mouth.

Jejunal Feeding Tube – A tube inserted into the jejunum via the stomach for long-term nutrition administration.

Jervell and Lange-Nielsen Syndrome – A rare inherited heart disorder that causes disturbances in the heart’s rhythm (arrhythmia).

Jock Itch – A fungal infection of the skin in the groin area, known medically as tinea cruris.

Joint Aspiration – A procedure involving the withdrawal of fluid from a joint using a needle and syringe.

Joint Replacement – A surgical procedure in which parts of an arthritic or damaged joint are removed and replaced with a metal, plastic, or ceramic device called a prosthesis.

Jones Fracture – A break between the base and middle part of the fifth metatarsal of the foot.

Juvenile Polyps – Benign (noncancerous) polyps that occur in children in the colon.

Juxtapapillary – Located near the optic disc in the eye.

Juxtaglomerular Cells – Cells in the kidney that synthesize, store, and secrete the enzyme renin.

Juxtamedullary Nephron – A nephron with a glomerulus close to and a long loop of Henle extending deep into the medulla; important for concentrating urine.

Juxtaposition – The act or position of placing two things next to each other or close together, often in medical contexts related to anatomical structures.

---

K

Kaposi’s Sarcoma – A type of cancer that forms in the lining of blood and lymph vessels.

Karyotype – The number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

Keratitis – Inflammation of the cornea.

Kernicterus – A type of brain damage that can result from high levels of bilirubin in a baby’s blood.

Ketamine – A medication mainly used for starting and maintaining anesthesia.

Ketoacidosis – A serious complication of diabetes that occurs when your body produces high levels of blood acids called ketones.

Ketones – Chemicals that the body creates when it breaks down fats to use for energy.

Ketosis – A metabolic state characterized by raised levels of ketone bodies in the body tissues.

Ketorolac – A nonsteroidal anti-inflammatory drug (NSAID) used to treat pain.

Kilocalorie – A unit of energy equal to 1,000 calories, commonly used to express the energy value of foods (calorie).

Kinesiology – The scientific study of human or non-human body movement.

Kinesthetic – Relating to a person’s awareness of the position and movement of the parts of the body.

Klinefelter Syndrome – A genetic condition in males in which they have an extra X chromosome.

Knee Arthroplasty – Surgical reconstruction or replacement of a knee joint.

Knee Joint – A joint that connects the upper leg to the lower leg.

Kneecap (Patella) – A small flat triangular bone in front of the knee that protects the knee joint.

Kyphosis – A forward rounding of the back.

KUB (Kidney, Ureter, and Bladder) – An X-ray study that allows visualization of the abdominal area including the kidneys, ureters, and bladder.

Kuru – A rare and fatal nervous system disease.

Kyphoplasty – A surgical procedure used to treat fractures in the vertebrae.

Keratin – A fibrous protein forming the main structural constituent of hair, feathers, hoofs, claws, horns, etc.

Keratoconus – A progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape.

Keratoplasty – Surgical replacement of part of the cornea.

Keratotomy – Surgical incision in the cornea.

Karyokinesis – The process of nuclear division in cells that occurs when the nucleus divides, resulting in the formation of two new nuclei.

Ketoconazole – An antifungal medication used to treat a variety of fungal infections.

Keratinocyte – A type of cell that makes up approximately 90% of the cells in the epidermis, the outer layer of the skin.

Kallmann Syndrome – A genetic disorder that prevents a person from starting or fully completing puberty.

Kinase – An enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates.

Kleptomania – A recurrent urge to steal, typically without regard for need or profit.

Klumpke’s Palsy – A form of paralysis involving the muscles of the forearm and hand, a result of injury to the brachial plexus.

Knock-Knees – A condition in which the knees angle in and touch one another when the legs are straightened.

Kohler Disease – A rare bone disorder of the foot found in children due to temporary loss of blood supply to the bone.

Kojic Acid – A chemical produced from different types of fungi used for cosmetic and medicinal purposes to lighten visible sun damage, age spots, or scars.

Krabbe Disease – A rare, often fatal degenerative disorder that affects the nervous system.

Kussmaul Breathing – Deep, labored breathing pattern often associated with severe metabolic acidosis, particularly diabetic ketoacidosis.

Kyphoscoliosis – A combination of outward and lateral curvature of the spine.

Kernig’s Sign – A clinical sign to evaluate suspected meningitis, characterized by stiffness in the hamstrings causing inability to straighten the leg when the hip is flexed.

Kartagener Syndrome – A genetic disorder characterized by the triad of chronic sinusitis, bronchiectasis, and situs inversus.

Keratoderma – Thickening of the skin’s outer layer.

Karyotyping – The process by which photographs of chromosomes are taken in order to determine the chromosome complement of an individual, including the number of chromosomes and any abnormalities.

Kidd Blood Group – A blood type system that can influence a person’s reaction to blood transfusions.

Kaplan-Meier Estimator – A statistic used in medical research to measure the fraction of patients living for a certain amount of time after treatment.

Kangaroo Care – A method of holding a baby that involves skin-to-skin contact.

Kava – A beverage or extract that is made from Piper methysticum, a plant native to the western Pacific islands, and used as a sedative.

Keratolytic – A class of drugs used to dissolve the outer layer of the skin.

Kwashiorkor – A form of severe protein malnutrition characterized by swelling and an enlarged liver with fatty infiltrates.

Karyorrhexis – The destructive fragmentation of the nucleus of a dying cell wherein its chromatin is distributed irregularly throughout the cytoplasm.

Kinesthetic Sense – Awareness of the position and movement of the parts of the body by means of sensory organs in the muscles and joints.

Killer Cells – White blood cells that attack tumor cells and body cells that have been invaded by foreign agents.

---

L

Labial – Pertaining to the lips.

Laceration – A deep cut or tear in skin or flesh.

Lactase – An enzyme that breaks down lactose into glucose and galactose.

Lactation – The secretion of milk by the mammary glands.

Laminectomy – A surgical operation to remove the back part of one or more vertebrae, usually to give access to the spinal cord or to relieve pressure on nerves.

Laparoscopy – A surgical diagnostic procedure used to examine the organs inside the abdomen.

Laparotomy – A surgical incision into the abdominal cavity, for diagnosis or in preparation for surgery.

Laryngectomy – Surgical removal of the larynx and separation of the airway from the mouth, nose and esophagus.

Laryngitis – Inflammation of the larynx, typically resulting in huskiness or loss of voice, harsh breathing, and a painful cough.

Larynx – The hollow muscular organ forming an air passage to the lungs and holding the vocal cords; the voice box.

Latent – Hidden, dormant, or inactive, particularly referring to a period where a disease is present but not active.

Lateral – Of, at, toward, or from the side or sides.

Laxative – A substance used to promote bowel movements.

LDL (Low-Density Lipoprotein) – Often called ‘bad’ cholesterol, it carries cholesterol from the liver to cells and can lead to deposition in arteries.

Lesion – A region in an organ or tissue which has suffered damage through injury or disease.

Leukemia – A type of cancer of the blood or bone marrow characterized by an abnormal increase of white blood cells.

Leukocyte – A white blood cell.

Leukocytosis – Increase in the number of white cells in the blood, especially during an infection.

Leukopenia – A decrease in the number of white cells in the blood, typical of various diseases.

Ligament – A short band of tough, flexible, fibrous connective tissue that connects two bones or cartilages or holds together a joint.

Lipase – An enzyme that catalyzes the breakdown of fats to fatty acids and glycerol.

Lipid – Any of a group of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents.

Lipoma – A benign tumor composed of adipose tissue (body fat).

Lipoprotein – Any of a group of soluble proteins that combine with and transport fat or other lipids in the blood plasma.

Lithotripsy – A medical procedure involving the physical destruction of hardened masses like kidney stones, bladder stones, or gallstones.

Liver – A large lobed glandular organ in the abdomen of vertebrates, involved in many metabolic processes.

Lobectomy – Surgical removal of a lobe of an organ such as the thyroid gland, lung, or liver.

Local Anesthesia – Loss of sensation in a small, specific area of the body.

Lumbar – Relating to the lower part of the back.

Lumpectomy – Surgical removal of a discrete portion or “lump” from an organ, especially from the breast.

Lumen – The inside space of a tubular structure, such as an artery or intestine.

Lupus – An autoimmune disease that can cause inflammation and pain in any part of your body.

Lymph – A colorless fluid containing white blood cells, which bathes the tissues and drains through the lymphatic system into the bloodstream.

Lymphadenopathy – Disease affecting lymph nodes.

Lymphangioma – A benign tumor that forms from lymphatic vessels.

Lymphatic System – The network of vessels through which lymph drains from the tissues into the blood.

Lymphedema – Swelling due to an abnormal accumulation of lymph fluid within the tissues.

Lymphocyte – A type of white blood cell that is part of the immune system.

Lymphoma – A group of blood cancers that develop from lymphocytes.

Lyophilization – A freeze-drying process used for the preservation of perishable materials.

Lysozyme – An enzyme that damages bacterial cell walls.

Lysis – The disintegration of a cell by rupture of the cell wall or membrane.

Lysosome – An organelle in the cytoplasm of eukaryotic cells containing degradative enzymes enclosed in a membrane.

Labrum – A ring of cartilage that follows the outside rim of the socket of ball-and-socket joints.

Lactobacillus – A genus of bacteria used in the production of yogurt and other fermented products.

Lacrimal Glands – The glands located in the upper outer region of each orbit which produce tears.

Lactation Consultant – A health professional who specializes in the clinical management of breastfeeding.

Laparoscope – An instrument used during laparoscopy to look at the abdominal organs.

Laryngoscope – An instrument used to examine the larynx, or voice box.

Laser Surgery – Use of a laser in surgery to cut or destroy tissue.

---

M

Macula – A small spot in the retina where vision is sharpest.

Magnetic Resonance Imaging (MRI) – A diagnostic technique that uses magnetic fields and radio waves to produce a detailed image of the body’s internal structures.

Malaria – A mosquito-borne infectious disease affecting humans and other animals caused by parasitic protozoans.

Malignant – Referring to the presence of cancerous cells that have the ability to spread to other sites in the body or to invade and destroy tissues.

Mammogram – An X-ray picture of the breast used to screen for breast cancer.

Mandible – The lower jawbone.

Mania – A mental illness marked by periods of great excitement, euphoria, delusions, and overactivity.

Mastectomy – Surgical removal of one or both breasts, partially or completely.

Maxilla – The upper jawbone in humans and other vertebrates.

Measles – A highly contagious infectious disease caused by the measles virus.

Mediastinum – The area between the lungs that contains the heart, esophagus, trachea, and thymus.

Medical Ethics – Principles and moral values that apply to the practice of medicine.

Medication – A drug used to diagnose, cure, treat, or prevent disease.

Melanoma – The most serious type of skin cancer.

Meningitis – Inflammation of the brain and spinal cord membranes, typically caused by an infection.

Meniscus – A piece of cartilage that provides a cushion between your femur (thigh bone) and tibia (shinbone).

Menopause – The time that marks the end of a woman’s menstrual cycles.

Metabolism – The chemical processes that occur within a living organism in order to maintain life.

Metacarpal – Any of the five bones in the hand.

Metastasis – The spread of cancer cells to new areas of the body.

Microbiology – The study of microscopic organisms, such as bacteria, viruses, archaea, fungi, and protozoa.

Microscope – An instrument used to see objects that are too small for the naked eye.

Midwife – A professional in midwifery, specializing in pregnancy, childbirth, postpartum, women’s sexual and reproductive health, and newborn care.

Migraine – A type of headache characterized by severe pain, often accompanied by nausea and sensitivity to light and sound.

Mitosis – A process where a single cell divides into two identical daughter cells (cell division).

Molar – Teeth specialized for grinding food, located in the back of the mouth.

Molecule – The smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms.

Monocyte – A type of white blood cell that fights off bacteria, viruses, and fungi.

Morbidity – The condition of being diseased or the incidence of illness in a population.

Mortality – The state of being subject to death.

MRI (Magnetic Resonance Imaging) – A medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body.

Mucous Membrane – A layer of cells that line body cavities and canals that lead to the outside, such as the nose, ears, and mouth.

Multiple Sclerosis – A disease in which the immune system eats away at the protective covering of nerves.

Mumps – A contagious disease caused by a virus that usually spreads through saliva and can infect many parts of the body, especially the parotid salivary glands.

Muscle – A tissue composed of fibers capable of contracting to effect bodily movement.

Musculoskeletal – Relating to or involving the muscles and the skeleton.

Mutation – The changing of the structure of a gene, resulting in a variant form that may be transmitted to subsequent generations.

Myalgia – Muscle pain.

Myasthenia Gravis – A chronic autoimmune neuromuscular disease that causes weakness in the skeletal muscles.

Mycology – The branch of biology concerned with the study of fungi, including their genetic and biochemical properties.

Myelin – A fatty substance that surrounds and insulates the axons of some nerve cells.

Myeloma – A type of cancer that begins in the plasma cells of bone marrow.

Myocardial Infarction – Another term for a heart attack.

Myocardium – The muscular tissue of the heart.

Myopia – Nearsightedness.

Myositis – Inflammation or degeneration of muscle tissue.

Mysthenia – A state of abnormal weakness or fatigue.

Myxedema – A severe form of hypothyroidism.

Myxoma – A benign tumor derived from connective tissue, characterized by soft, gelatinous consistency.

Metatarsal – Any of the bones in the foot of a vertebrate between the phalanges and the tarsals.

---

N

Narcotic – A drug affecting mood or behavior, sold for nonmedical purposes, especially an illegal one.

Nasal – Pertaining to the nose.

Nasogastric Tube (NG Tube) – A tube inserted through the nose into the stomach for feeding or drainage.

Nausea – A feeling of sickness with an inclination to vomit.

Necrosis – The death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply.

Nephrectomy – Surgical removal of one or both kidneys.

Nephritis – Inflammation of the kidneys.

Nephrology – The branch of medicine that deals with the physiology and diseases of the kidneys.

Nephron – The functional unit of the kidney, involved in the process of filtering the blood and forming urine.

Nerve Conduction Study – A medical diagnostic test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body.

Neuralgia – Intense, typically intermittent pain along the course of a nerve, especially in the head or face.

Neuritis – Inflammation of a nerve or the general inflammation of the peripheral nervous system.

Neuroblastoma – A cancer that develops from immature nerve cells found in several areas of the body.

Neurology – The branch of medicine or biology that deals with the anatomy, functions, and organic disorders of nerves and the nervous system.

Neuroma – A growth or tumor of nerve tissue.

Neuropathy – Disease or dysfunction of one or more peripheral nerves, typically causing numbness or weakness.

Neurotransmitter – Chemical substances that transmit nerve impulses across a synapse.

Neutropenia – A decrease in the number of neutrophils, a type of white blood cell, in the blood.

Nevus – A birthmark or a mole on the skin, especially a birthmark in the form of a raised red patch.

Nicotine – A toxic colorless or yellowish oily liquid that is the chief active constituent of tobacco, causing addiction and increases in blood pressure.

Night Blindness – The inability to see well at night or in poor light.

Nocturia – Excessive urination at night.

Nodule – A small swelling or aggregation of cells in the body, especially an abnormal one.

Non-Invasive – Not involving the introduction of instruments into the body.

Norepinephrine – A hormone that is used medically to treat low blood pressure; it functions as a neurotransmitter in the brain.

Nasopharynx – The upper part of the pharynx, connecting with the nasal cavity above the soft palate.

Nebulizer – A device for producing a fine spray of liquid, used for inhaling a medicinal drug.

Necrotizing Fasciitis – A rare bacterial infection that spreads quickly in the body and can cause death. Skin, muscle, and fat tissue may be destroyed.

Negative Feedback – A reaction that causes a decrease in function in response to some kind of stimulus.

Neonatology – A subspecialty of pediatrics that consists of the medical care of newborn infants, especially the ill or premature newborn.

Nephrolithiasis – Kidney stones; a condition marked by the presence of renal calculi.

Neti Pot – A device used for irrigating the nasal passages, typically to relieve the symptoms of sinusitis and other respiratory conditions.

Neural Tube Defect – A birth defect of the brain, spine, or spinal cord happening in the first month of pregnancy resulting from the failure of the spine and skull to close properly.

Neurodegenerative – Relating to or affected by the degeneration of the nervous system.

Neuroendocrine – Relating to nerves and glands, or to the control of bodily functions by the nervous system.

Neurofibromatosis – A genetic disorder that causes tumors to form on nerve tissue.

Neurogenic Bladder – A urinary bladder malfunction caused by a nervous system disorder.

Neurology – The medical specialty dealing with disorders of the nervous system.

Neuromodulation – The physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons.

Neuron – A specialized cell transmitting nerve impulses; a nerve cell.

Neuropeptide – Any of various peptides found in neural tissue, acting as a neurotransmitter or neuromodulator.

Neuroplasticity – The ability of the brain to form and reorganize synaptic connections, especially in response to learning or experience or following injury.

Neuroscience – The scientific study of the nervous system.

Neurosurgeon – A medical specialist who performs surgery on the nervous system, especially the brain and spinal cord.

Neurotic – Suffering from, caused by, or relating to neurosis.

Neutralize – To counteract or cancel the effect of.

Neutrophil – A type of white blood cell that helps heal damaged tissues and resolve infections.

Newborn Screening – Tests performed on newborns to screen for serious or life-threatening conditions.

Nipple – The small projection in which the mammary ducts of female mammals terminate and from which milk can be secreted.

Nitroglycerin – A heavy, colorless, oily, explosive liquid used in medicine as a vasodilator to treat heart conditions.

---

O

Obesity – A medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health.

Obstetrics – A branch of medicine and surgery concerned with childbirth and the care of women giving birth.

Occlusion – The blockage or closing of a blood vessel or hollow organ.

Occupational Therapy – Therapy aimed at helping people achieve independence in all facets of their lives.

Ocular – Pertaining to the eye.

Odontalgia – Tooth pain or toothache.

Olfaction – The sense of smell.

Oliguria – The production of abnormally small amounts of urine.

Oncology – The study and treatment of tumors and cancer.

Oophorectomy – Surgical removal of one or both ovaries.

Open Reduction Internal Fixation (ORIF) – A type of surgery used to fix broken bones.

Ophthalmology – The branch of medicine concerned with the study and treatment of disorders and diseases of the eye.

Opioids – A broad group of pain-relieving drugs that work by interacting with opioid receptors in your cells.

Optician – A technical practitioner who designs, fits, and dispenses corrective lenses for the correction of a person’s vision.

Optometry – The practice or profession of examining the eyes for visual defects and prescribing corrective lenses.

Oral – Pertaining to the mouth.

Orchiectomy – Surgical removal of one or both testicles.

Orthodontics – A branch of dentistry dealing with the correction of teeth and jaws that are positioned improperly.

Orthopedics – The branch of medicine dealing with the correction of deformities of bones or muscles.

Orthostatic Hypotension – A form of low blood pressure that happens when you stand up from sitting or lying down.

Osteoarthritis – A type of arthritis that occurs when flexible tissue at the ends of bones wears down.

Osteoblast – A cell that secretes the matrix for bone formation.

Osteoclast – A large multinucleate bone cell that absorbs bone tissue during growth and healing.

Osteogenesis – The formation of bone.

Osteomalacia – Softening of the bones, typically through a deficiency of vitamin D or calcium.

Osteomyelitis – Inflammation of bone or bone marrow, usually due to infection.

Osteoporosis – A medical condition in which the bones become brittle and fragile from loss of tissue.

Osteosarcoma – A type of bone cancer that begins in the cells that form bones.

Ostomy – A surgical procedure creating an opening for the body to discharge waste.

Otitis Media – Inflammation of the middle ear.

Otolaryngology – The study of diseases of the ear and throat.

Otorhinolaryngology – The study of diseases of the ear, nose, and throat.

Otoscope – A device used to look into the ears.

Ovarian Cyst – A solid or fluid-filled sac or pocket (cyst) within or on the surface of an ovary.

Overdose – The ingestion or application of a drug or other substance in quantities greater than are recommended.

Ovulation – The release of an egg from one of a woman’s ovaries.

Oxidation – The combination of a substance with oxygen.

Oxygen Therapy – The administration of oxygen as a medical intervention.

Oxytocin – A hormone that acts as a neurotransmitter in the brain and plays a significant role in childbirth and lactation.

Ozone Therapy – A form of alternative treatment that increases the amount of oxygen in the body through the introduction of ozone.

Oophoritis – Inflammation of the ovaries.

Ophthalmoscope – An instrument used to examine the interior of the eye.

Osteochondritis – Inflammation of bone and cartilage tissues.

Osteopenia – Thinning of the bones, less severe than osteoporosis.

Ostium – An opening or orifice in the body.

Oropharyngeal – Pertaining to the mouth and pharynx.

Orthokeratology – A method of reshaping the eye to correct myopia (nearsightedness).

Orthopnea – Shortness of breath (dyspnea) that occurs when lying flat.

Oscilloscope – An electronic device used for displaying the waveform of electrical signals.

Ovum – A mature female reproductive cell, which can divide to give rise to an embryo usually only after fertilization by a male cell.

---

P

Pacemaker – A device that regulates the heartbeat using electrical impulses.

Palpation – The process of using one’s hands to check the body, especially while diagnosing a disease or illness.

Pancreatitis – Inflammation of the pancreas.

Pandemic – An epidemic of infectious disease that has spread across a large region, for instance multiple continents or worldwide.

Pap Smear – A procedure to test for cervical cancer in women.

Paracentesis – A procedure to remove fluid from the abdomen using a needle.

Paralysis – The loss of the ability to move some or all of the body.

Paraplegia – Impairment in motor or sensory function of the lower extremities.

Parathyroid Glands – Small glands of the endocrine system which regulate calcium levels in the blood.

Parenteral – Administered or occurring elsewhere in the body than the mouth and alimentary canal.

Parkinson’s Disease – A degenerative disorder of the central nervous system that often impairs motor skills and speech.

Pathogen – A bacterium, virus, or other microorganism that can cause disease.

Pathology – The science of the causes and effects of diseases, especially the branch of medicine that deals with the laboratory examination of samples of body tissue for diagnostic or forensic purposes.

Pediatrics – The branch of medicine dealing with children and their diseases.

Pelvic Inflammatory Disease (PID) – Inflammation of the female reproductive organs.

Peptic Ulcer – A sore that develops on the lining of the esophagus, stomach, or small intestine.

Perfusion – The passage of fluid through the lymphatic system or blood vessels to an organ or a tissue.

Pericarditis – Inflammation of the pericardium, the fibrous sac surrounding the heart.

Peripheral Neuropathy – A result of damage to peripheral nerves, often causes weakness, numbness, and pain, usually in your hands and feet.

Peritoneum – The serous membrane lining the cavity of the abdomen and covering the abdominal organs.

Pernicious Anemia – A decrease in red blood cells when the body can’t absorb enough vitamin B-12.

PET Scan (Positron Emission Tomography Scan) – An imaging test that helps reveal how your tissues and organs are functioning.

Phalanges – Bones in the fingers and toes.

Pharmacology – The branch of medicine and biology concerned with the study of drug action.

Phlebotomy – The process of making an incision in a vein with a needle.

Photophobia – Sensitivity to light.

Physical Therapy – Treatment to prevent disability or restore function through the use of exercise, heat, massage, or other techniques.

Physiology – The branch of biology that deals with the normal functions of living organisms and their parts.

Pituitary Gland – The major endocrine gland, a pea-sized body attached to the base of the brain that controls growth and development.

Placebo – A substance with no therapeutic effect, used as a control in testing new drugs.

Placenta – An organ that develops in the uterus during pregnancy to provide oxygen and nutrients to the growing baby while removing waste products.

Plasma – The liquid part of blood or lymph, as distinguished from the suspended elements.

Platelets – Small blood cells that help the clotting process by sticking together and sealing small breaks in blood vessels.

Pleura – The membrane surrounding the lungs and lining the chest cavity.

Pleural Effusion – A buildup of fluid between the tissues that line the lungs and the chest.

Pneumonia – Inflammation of the lungs caused by bacterial, viral, or fungal infection.

Podiatry – The branch of medicine that deals with the diagnosis and treatment of disorders of the foot, ankle, and lower extremity.

Polycystic Ovary Syndrome (PCOS) – A hormonal disorder causing enlarged ovaries with small cysts on the outer edges.

Polydipsia – Excessive thirst or excess drinking.

Polymerase Chain Reaction (PCR) – A method widely used to rapidly make millions to billions of copies of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it to a large enough amount to study in detail.

Polyp – An abnormal growth of tissue projecting from a mucous membrane.

Postpartum – The period just after childbirth.

Pre-eclampsia – A pregnancy complication characterized by high blood pressure and signs of damage to another organ system, most often the liver and kidneys.

Prognosis – The likely course of a disease or ailment.

Prolapse – The slipping forward or down of one of the parts or organs of the body.

Prophylaxis – Action taken to prevent disease, especially by specified means or against a specified disease.

Prostate – A gland surrounding the neck of the bladder in male mammals and releasing prostatic fluid.

Prosthesis – An artificial body part, such as a leg, a heart, or a breast implant.

Proteinuria – The presence of abnormal quantities of protein in the urine, which may indicate damage to the kidneys.

Psoriasis – A skin disease marked by red, itchy, scaly patches.

---

Q

Quadrantectomy – A surgical procedure where a quarter of the breast is removed, typically performed as a treatment for breast cancer.

Quadriplegia – Paralysis of all four limbs; tetraplegia.

Quarantine – A restriction on the movement of people and goods, which is intended to prevent the spread of disease or pests.

Quartile – A statistical term describing a division of a data set into four defined intervals.

Quasi-experiment – A type of research design that attempts to establish a cause-and-effect relationship where strict randomization is not feasible.

Queckenstedt’s Test – A diagnostic test in which the venous plexus of the neck is compressed to increase intracranial pressure, thereby testing for blockages in spinal fluid pathways.

Quickening – The first movements of the fetus in the uterus as felt by the pregnant woman, typically between the 16th and 25th weeks of pregnancy.

Quincke’s Disease – Another name for angioedema, which is rapid swelling of the dermis, subcutaneous tissue, mucosa, and submucosal tissues.

Quinsy – A complication of tonsillitis, a peritonsillar abscess.

Quinine – A medication used to treat malaria and babesiosis, which includes the treatment of chloroquine-resistant malaria.

QRS Complex – The combination of three of the graphical deflections seen on a typical electrocardiogram (EKG), representing a complete heartbeat from ventricular depolarization and repolarization.

Quantitative Research – Research that collects and analyzes numerical data to understand patterns, relationships, or to predict outcomes.

Quadriceps Tendon – The tendon of the quadriceps femoris muscle, which extends the knee and stabilizes the patella.

Quadriceps Strength Test – A clinical test used to assess the strength and function of the quadriceps muscle, especially in rehabilitation settings.

---

R

Radiology – The science dealing with X-rays and other high-energy radiation, especially the use of such radiation for the diagnosis and treatment of disease.

Radiopaque – Materials that do not allow X-rays or other radiation to pass through.

Radial – Pertaining to the radius (bone in the forearm) or relating to any radius or radial structure.

Radiotherapy – The treatment of disease, especially cancer, using X-rays or similar forms of radiation.

Rales – Abnormal rattling sound heard when examining unhealthy lungs with a stethoscope.

Randomized Controlled Trial (RCT) – A type of scientific experiment that aims to reduce certain sources of bias when testing the effectiveness of new treatments.

Range of Motion (ROM) – The full movement potential of a joint, usually its range of flexion and extension.

Receptor – A specialized cell or group of nerve endings that responds to sensory stimuli.

Recessive – Referring to a gene that produces its characteristic phenotype only when its allele is identical.

Reconstructive Surgery – Surgery performed to restore appearance or function lost due to injury, disease, or birth defects.

Recurrence – The return of a sign, symptom, or disease after a remission.

Reflux – The process of flowing back or returning, particularly of fluids.

Regurgitation – The backward flowing of undigested food or fluids through the esophagus and mouth.

Rehabilitation – The process of restoring someone to health or normal life through training and therapy after imprisonment, addiction, or illness.

Relapse – The return of a disease or the signs and symptoms of a disease after a patient has recovered.

Remission – A decrease or disappearance of signs and symptoms of cancer or other disease.

Renal – Pertaining to the kidneys.

Reproductive Health – A state of physical, mental, and social well-being in all matters relating to the reproductive system.

Resection – The surgical removal of part of an organ or structure.

Residual – Remaining after the greater part or quantity has gone.

Resistance – The ability of an organism to defend itself against a disease or withstand the effects of a drug.

Respiration – The action of breathing.

Respiratory Rate – The number of breaths a person takes per minute.

Retina – A layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.

Retrovirus – A type of virus that has RNA as its genetic material and uses the enzyme reverse transcriptase to copy its RNA into DNA.

Rheumatoid Arthritis – A chronic inflammatory disorder affecting many joints, including those in the hands and feet.

Rhinitis – Inflammation of the mucous membrane of the nose, caused by a virus infection or by an allergic reaction.

Rhonchi – Low-pitched, rattling sounds in the lungs that can be heard through a stethoscope and often sound like snoring.

Rickets – A disease of children caused by vitamin D deficiency, characterized by imperfect calcification, softening, and distortion of the bones.

Risk Factor – Anything that increases an individual’s likelihood of developing a disease or injury.

RNA (Ribonucleic Acid) – A nucleic acid present in all living cells. Its principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins.

Rotator Cuff – A group of muscles and tendons that surround the shoulder joint.

Rubella – A contagious viral disease, with symptoms like mild measles. It can cause fetal malformation if contracted by a mother during pregnancy.

Rubeola – Another term for measles, a viral disease causing fever and a red rash.

Rupture – An instance of breaking or bursting suddenly and completely.

Rhabdomyolysis – A serious syndrome due to a direct or indirect muscle injury.

Rhinoplasty – Cosmetic surgery performed on the nose.

Radiograph – An image produced on a sensitive plate or film by X-rays, gamma rays, or similar radiation, and typically used in medical examination.

Radionuclide – A radioactive nuclide.

Radiofrequency – Radiation used in various medical applications, including heating tissues for therapeutic purposes.

Recurrent – Occurring often or repeatedly.

Refractory – Not yielding to treatment or cure.

Regional Anesthesia – Anesthesia affecting only a large part of the body.

Regurgitate – Bring (swallowed food) up again to the mouth.

Rehydration – The process of restoring lost water (hydration) to the body tissues and fluids.

Rejection – The failure of the body to accept a transplanted organ or tissue.

Relaxation Therapy – Techniques that help reduce stress and anxiety by relaxing the muscles.

Remodeling – The process by which bone or tissue is renewed and reshaped.

Reproductive System – The organs and glands in the body that aid in the production of new individuals (reproduction).

Resection – Surgical removal of a part of an organ or structure.

Residual Volume – The volume of air remaining in the lungs after a maximal exhalation.

Respiratory Failure – A condition in which the respiratory system fails in one or both of its gas exchange functions.

Respiratory Syncytial Virus (RSV) – A virus that causes respiratory tract infections; it is a major cause of respiratory illness in young children.

Restenosis – The reoccurrence of stenosis, a narrowing of a blood vessel, leading to restricted blood flow.

Restrictive Lung Disease – A group of lung diseases that prevent the lungs from fully expanding with air.

Retinopathy – Any damage to the retina of the eyes, which may cause vision impairment.

Retroperitoneal – Situated or occurring behind the peritoneum.

Rheumatic Fever – An inflammatory disease that can develop as a complication of poorly treated strep throat or scarlet fever.

Rheumatism – An umbrella term for conditions causing chronic, often intermittent pain affecting the joints and/or connective tissue.

Rheumatologist – A physician who specializes in the diagnosis and treatment of rheumatic diseases.

Rhinorrhea – Excessive mucus secretion from the nose, a runny nose.

Rickets – A condition in children caused by a deficiency of vitamin D, calcium, or phosphate, leading to softening and weakening of the bones.

Right-to-Try Law – Federal laws that allow terminally ill patients to try experimental treatments not yet approved by the FDA.

Risk Assessment – A systematic process of evaluating the potential risks that may be involved in a projected activity or undertaking.

Robot-Assisted Surgery – A type of surgery performed using robotic systems, which provides a magnified 3D view of the surgical site.

Root Canal – A treatment to repair and save a badly damaged or infected tooth instead of removing it.

Rosacea – A chronic skin condition that causes redness and pimples on the face.

Rotavirus – A virus that causes diarrhea, mostly in babies and young children.

Round Ligament – A ligament that connects the front of the uterus to the groin region.

Rubor – Redness of the skin, typically due to injury or inflammation.

Rubeosis – Abnormal new blood vessel formation on the surface of a structure, usually the eye.

Rubella – A contagious viral disease causing a mild fever and a rash of pink spots. It can cause birth defects if contracted by a pregnant woman.

Rumination Disorder – A condition in which a person regurgitates food they have previously chewed and swallowed, re-chews it, and then either re-swallows it or spits it out.

Runner’s Knee – A common knee condition with pain around the patella (kneecap), formally known as patellofemoral pain syndrome.

Ruptured Disc – A condition where a spinal disc breaks open, releasing the gel-like material inside, which can irritate nearby nerves.

Rust Ring – A deposit of iron in the cornea, usually from a metallic foreign body.

Ruthenium-106 – A radioactive compound used in radiation therapy for eye tumors.

Rygb Surgery – Roux-en-Y gastric bypass, a type of weight-loss surgery.

Retrograde – Moving backward or deteriorating from a previous standard.

Retroperitoneal Fibrosis – A rare disorder characterized by the presence of fibrous plaques in the tissue behind the peritoneum of the abdominal cavity.

Retropulsion – The act of pushing backward, often used to describe a symptom in Parkinson’s disease where a patient steps backward uncontrolledly.

Retroversion – A turning or tilting backward of an organ, such as the uterus.

Revascularization – Restoration of blood supply to a body part or organ that has suffered from a lack of blood flow.

Revaccination – The process of administering a vaccine additional times after the initial vaccination.

Rhabdomyolysis – A potentially life-threatening syndrome resulting from the breakdown of muscle fibers and release of their contents into the bloodstream.

Rhizotomy – A surgical procedure to sever nerve roots in the spinal cord, often to relieve chronic pain.

Rhonchus – A wheezing sound heard during auscultation of the lungs.

Rhytidectomy – A surgical procedure, often called a facelift, to reduce wrinkles and improve visible signs of aging in the face and neck.

Rhythm Method – A natural form of birth control that involves tracking the menstrual cycle to determine the days that a woman is most likely to be fertile.

Ribonucleotide – A type of molecule that forms the basic building block of RNA.

Ribose – A simple sugar and carbohydrate component of RNA.

Ribosome – A complex molecular machine found within all living cells that serves as the site of biological protein synthesis (translation).

Rickets – A softening and weakening of bones in children, usually due to inadequate vitamin D.

Rickettsia – A genus of nonmotile, gram-negative, non-spore-forming, highly pleomorphic bacteria that can be transmitted to humans by arthropods.

Rift Valley Fever – An acute fever caused by a viral zoonosis that primarily affects animals but can also infect humans.

Rigid Fixation – A type of surgical technique used to stabilize bones or joints, typically using screws and plates.

Rigor Mortis – The stiffening of the joints and muscles of a body a few hours after death.

Ringworm – A highly contagious, fungal infection of the skin or scalp.

Ristocetin Cofactor – A laboratory test used to investigate bleeding disorders.

RNA Polymerase – An enzyme that synthesizes RNA from a DNA template during transcription.

---

S

Sacroiliac – Pertaining to the sacrum and the ilium.

Salpingectomy – Surgical removal of a fallopian tube.

Sarcoma – A type of cancer that arises from transformed cells of mesenchymal origin.

Saturated Fat – A type of fat containing a high proportion of fatty acid molecules without double bonds, considered less healthy in the diet than unsaturated fat.

Scabies – A contagious skin disease caused by the itch mite, characterized by intense itching.

Scapula – The shoulder blade.

Sciatica – Pain affecting the back, hip, and outer side of the leg, caused by compression of a spinal nerve root in the lower back.

Sclera – The white outer layer of the eyeball.

Scleroderma – A group of autoimmune diseases that may result in changes to the skin, blood vessels, muscles, and internal organs.

Scoliosis – A sideways curvature of the spine.

Scotoma – A partial loss of vision or a blind spot in an otherwise normal visual field.

Sebaceous Glands – Small oil-producing glands present in the skin of mammals.

Sedation – The administration of a sedative drug to produce a state of calm or sleep.

Sedative – A substance that induces sedation by reducing irritability or excitement.

Sepsis – A life-threatening condition that arises when the body’s response to infection causes injury to its own tissues and organs.

Septicemia – Blood poisoning, especially that caused by bacteria or their toxins.

Serotonin – A compound present in blood platelets and serum, which constricts the blood vessels and acts as a neurotransmitter.

Serum – The component of blood that is typically a clear liquid and separates out when blood coagulates.

Shingles – A viral infection causing a painful rash, typically appearing as a stripe of blisters on the body.

Shock – A critical condition brought on by the sudden drop in blood flow through the body, often as a result of severe blood loss or an allergic reaction.

Sigmoidoscopy – An examination of the lower colon using a device called a sigmoidoscope.

Sinusitis – Inflammation of the lining of the sinuses.

Skeletal Muscle – Muscle that is connected to the skeleton to form part of the mechanical system that moves the limbs and other parts of the body.

Skin Graft – A type of graft surgery involving the transplantation of skin.

Sleep Apnea – A potentially serious sleep disorder in which breathing repeatedly stops and starts.

Smear Test – A method of detecting cervical cancer by taking a sample of cells from the cervix.

Somatic – Pertaining to the body, separate from the mind.

Spasm – A sudden involuntary muscular contraction or convulsive movement.

Spasticity – A condition in which certain muscles are continuously contracted.

Spectrophotometry – A method of measuring how much light a chemical substance absorbs by measuring the intensity of light as a beam passes through the sample solution.

Spermicide – A substance that kills sperm, used as a contraceptive.

Sphygmomanometer – An instrument for measuring blood pressure.

Spina Bifida – A birth defect where there is incomplete closing of the backbone and membranes around the spinal cord.

Spinal Cord – The major column of nerve tissue that is connected to the brain and lies within the spinal column.

Spirometer – An instrument for measuring the air capacity of the lungs.

Splenectomy – Surgical removal of the spleen.

Splint – A strip of rigid material used for supporting and immobilizing a broken bone when it has been set.

Spondylitis – Inflammation of the vertebrae.

Sprain – A stretching or tearing of ligaments, the fibrous tissue that connects bones and joints.

Sputum – Mucus and other matter brought up from the lungs by coughing.

Staphylococcus – A genus of gram-positive bacteria, which are potential pathogens, causing local lesions and serious opportunistic infections.

Stasis – A stoppage or slowdown in the flow of blood or other body fluid, such as lymph.

Stent – A tube inserted into the lumen of an anatomic vessel or duct to keep the passageway open.

Sterilization – Any process that eliminates or kills all forms of microbial life, including transmissible agents.

Sternum – The breastbone.

Stethoscope – An instrument used to listen to the sounds made by the heart, lungs, and other organs in the body.

Stimulant – A substance that raises levels of physiological or nervous activity in the body.

Strain – A force tending to pull or stretch something to an extreme or damaging degree.

Stratum Corneum – The outermost layer of the epidermis.

Streptococcus – A genus of coccus (spherical) bacteria, belonging to the phylum Firmicutes and the lactic acid bacteria group.

Stress Test – A test of cardiovascular capacity made by monitoring the heart rate during a period of increasingly strenuous exercise.

Stricture – An abnormal narrowing of a passage or opening.

Stroke – A sudden disabling attack or loss of consciousness caused by an interruption in the flow of blood to the brain, especially through thrombosis.

Subarachnoid Hemorrhage – Bleeding in the area between the brain and the thin tissues covering the brain.

Subcutaneous – Situated or applied under the skin.

Subluxation – A partial dislocation.

Substance Abuse – Overindulgence in or dependence on an addictive substance, especially alcohol or drugs.

Succussion – A medical procedure involving shaking the patient and listening to the sounds thus produced for diagnostic purposes.

Sudden Infant Death Syndrome (SIDS) – The sudden, unexpected death of a child under age one in which an autopsy does not show an explainable cause of death.

Suicide – The act of intentionally causing one’s own death.

Sulcus – A groove, natural division, deep furrow, elongated cleft, or tear in various parts, especially in the brain.

Superior – Higher in position.

Supination – The outward rotation of the forearm causing palms to face upward.

Suppository – A solid medical preparation in a roughly conical or cylindrical shape, designed to dissolve in the rectum or vagina.

Suppression – The act of stopping or restraining.

Supraventricular Tachycardia – An abnormally fast heartbeat that originates somewhere above the ventricles.

Surgical Asepsis – Techniques used to destroy all pathogenic organisms, as in the preparation of the operating area.

Sutures – Stitches used to hold tissue together.

Swab – A small piece of material used for cleaning a wound or collecting a sample of a substance.

Sweat Glands – Small tubular structures of the skin that produce sweat.

Sympathetic Nervous System – Part of the autonomic nervous system that serves to accelerate the heart rate, constrict blood vessels, and raise blood pressure.

Symptom – Any subjective evidence of disease.

Synapse – The junction between two nerve cells, where impulses pass by diffusion of a neurotransmitter.

Syncope – Temporary loss of consciousness caused by a fall in blood pressure.

Syndrome – A group of symptoms which consistently occur together, or a condition characterized by a set of associated symptoms.

Synergist – A substance, organ, or other agent that participates in an effect of synergy.

Synovial Fluid – The transparent viscid fluid secreted by the synovial membranes and acts as a lubricant for joints and tendons.

Synovial Joint – A type of joint that is surrounded by a fluid-filled capsule.

Synovitis – Inflammation of the synovial membrane that lines a synovial joint.

Systemic – Pertaining to or affecting the body as a whole.

Systemic Lupus Erythematosus (SLE) – An autoimmune disease in which the immune system attacks its own tissues, causing widespread inflammation and tissue damage in the affected organs.

Systole – The phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries.

Sclerotherapy – A medical procedure used to eliminate varicose veins and spider veins.

Sclerotic – Hardening of tissue, particularly due to excessive growth of fibrous tissue.

Somatic Cell – Any cell of the body except sperm and egg cells.

Somatostatin – A hormone that inhibits the release of growth hormone and insulin.

Somnolence – Sleepiness, the state of feeling drowsy or ready to fall asleep.

Sonogram – An image formed using ultrasound.

Spasticity – A condition in which certain muscles are continuously contracted.

Specialization – In medicine, the process of focusing on a specific area of practice.

Specimen – A sample taken for medical testing, especially of tissue for diagnostic purposes.

Sphincter – A ring of muscle surrounding and serving to guard or close an opening or tube, such as the anus or the openings of the stomach.

Spinal Tap – A procedure in which a needle is inserted into the spinal canal to collect cerebrospinal fluid for diagnostic testing.

Spirochete – A type of bacteria characterized by a flexible spirally twisted body.

Splenomegaly – Abnormal enlargement of the spleen.

Spondylosis – A painful condition of the spine resulting from the degeneration of the intervertebral discs.

Sporadic – Occurring at irregular intervals or only in a few places; scattered or isolated.

Staging – The process of determining the extent and spread of cancer within the body.

Stenosis – The abnormal narrowing of a passage in the body.

Sterility – The quality or condition of being sterile.

---

T

Tachycardia – An abnormally fast heart rate.

Tachypnea – Rapid breathing.

Tamponade – Compression of the heart caused by fluid accumulation in the pericardial sac.

Tarsal – Relating to the bones in the ankle and foot.

Tendinitis – Inflammation of a tendon.

Teratogen – Any agent that can cause a birth defect or negatively affect the development of an embryo or fetus.

Thoracentesis – A procedure to remove fluid or air from the chest.

Thoracic – Pertaining to the chest.

Thrombectomy – Surgical removal of a blood clot from a blood vessel.

Thrombocytopenia – A condition characterized by abnormally low levels of platelets in the blood.

Thrombosis – The formation of a blood clot inside a blood vessel.

Thyroidectomy – Surgical removal of the thyroid gland.

Tinnitus – Ringing or buzzing noise in one or both ears that may be constant or come and go.

Tissue Plasminogen Activator (tPA) – A protein involved in the breakdown of blood clots.

Titration – A method or process of determining the concentration of a dissolved substance.

Tolerance – The body’s ability to endure a higher dose of a drug without adverse effects.

Tomography – Imaging by sections or sectioning through the use of any kind of penetrating wave.

Tonsillectomy – Surgical removal of the tonsils.

Topical – Applied to a particular place on or in the body.

Toxicology – The study of the adverse effects of chemicals on living organisms.

Tracheostomy – A surgical procedure to create an opening through the neck into the trachea.

Transdermal – Crossing through the skin, typically referring to drug delivery systems.

Transfusion – The process of transferring blood or blood-based products from one person into the circulatory system of another.

Transplant – The transfer of an organ or tissue from one body to another or from one part of the body to another.

Trapezius – A large triangular muscle extending over the back of the neck and shoulders.

Tremor – An involuntary, rhythmic muscle contraction leading to shaking movements in one or more parts of the body.

Trichomoniasis – A sexually transmitted infection caused by a parasite.

Tricuspid Valve – A valve in the heart that lies between the right atrium and the right ventricle.

Trigeminal Neuralgia – A chronic pain condition affecting the trigeminal nerve in the face.

Trocar – A sharp-pointed surgical instrument fitted with a cannula, used to puncture the wall of a body cavity and withdraw fluid or gas.

Tubal Ligation – A surgical procedure for female sterilization involving severing and tying the fallopian tubes.

Tuberculosis – An infectious disease caused by the bacterium Mycobacterium tuberculosis, affecting mostly the lungs.

Tumor – An abnormal mass of tissue that may be solid or fluid-filled.

Tympanometry – An examination used to test the condition of the middle ear and mobility of the eardrum.

Type 1 Diabetes – A chronic condition in which the pancreas produces little or no insulin.

Type 2 Diabetes – A chronic condition that affects the way the body processes blood sugar (glucose).

Therapeutics – The branch of medicine concerned with the treatment of diseases and the practice of healing.

Thrombolytic – Relating to the dissolution of thrombi (blood clots).

Thoracoscopy – Endoscopic examination of the chest cavity.

Thrombophlebitis – Inflammation of the wall of a vein with associated thrombosis, often occurring in the legs during pregnancy.

Thallium Stress Test – A diagnostic test used in cardiology to evaluate the blood flow to the heart.

Thyroiditis – Inflammation of the thyroid gland.

Thoracotomy – A surgical incision into the chest wall.

Thalassemia – An inherited blood disorder characterized by less oxygen-carrying protein in the blood.

Therapeutic Index – The ratio between the toxic and therapeutic concentrations of a drug.

Torsion – The twisting of a bodily organ on its own axis.

Toxoplasmosis – An infection caused by a parasite transmitted most commonly by contact with cat feces or undercooked meat.

Tranquilizer – A drug that lowers anxiety and reduces tension.

Transillumination – The technique of passing light through body tissues for medical examination.

Transverse Fracture – A bone fracture that occurs at a right angle to the bone’s axis.

Trauma – A serious injury or shock to the body, as from violence or an accident.

Triage – The process of sorting people based on their need for immediate medical treatment.

Tricuspid Atresia – A form of congenital heart disease whereby there is a complete absence of the tricuspid valve.

Triglycerides – A type of fat (lipid) found in your blood.

Tuberculin Skin Test – A test used to determine if someone has developed an immune response to the bacterium that causes tuberculosis.

Tumor Marker – Substances that can be found in the body when cancer is present.

T-wave – A feature on an electrocardiogram (ECG) representing the repolarization of the ventricles.

Tachyarrhythmia – An abnormally fast heart rhythm.

Tactile – Pertaining to touch.

Telemetry – The remote monitoring of a patient’s vital signs.

Temporal Arteritis – Inflammation and damage to blood vessels that supply the head area, particularly the large or medium arteries that branch from the neck.

Tendonitis – See tendinitis.

Tenotomy – Surgical cutting of a tendon to relieve muscle tension.

Terminology – The body of terms used with a particular technical application in a subject of study, profession, etc.

Testosterone – The primary male sex hormone.

Thermotherapy – Treatment of disease by the application of heat.

Thoracic Surgery – Surgery performed on the thorax, excluding the heart.

Thyroid Hormones – Hormones produced by the thyroid gland primarily responsible for regulation of metabolism.

Tissue Engineering – The use of a combination of cells, engineering, and materials methods, and suitable biochemical and physicochemical factors to improve or replace biological tissues.

Tonic – A medicinal substance taken to give a feeling of vigor or well-being.

Topical Anesthesia – Anesthesia applied to the skin to numb a specific area.

Toxicity – The quality of being toxic or poisonous.

Toxoid – A modified toxin that has been made nontoxic but retains the ability to stimulate the formation of antitoxins, used in vaccines.

Trachea – The windpipe; the large membranous tube reinforced by rings of cartilage, extending from the larynx to the bronchial tubes and conveying air to and from the lungs.

Transcription – The process of making an RNA copy of a gene’s DNA sequence.

Transcutaneous – Across the skin.

Transfusion Reaction – An adverse reaction to a blood transfusion.

Transient Ischemic Attack (TIA) – A temporary period of symptoms similar to those of a stroke.

Transplant Rejection – When a transplant recipient’s immune system attacks the transplanted organ or tissue.

Traumatic Brain Injury (TBI) – A form of acquired brain injury occurs when a sudden trauma causes damage to the brain.

Trendelenburg Position – A position where the patient’s feet are higher than the head by 15-30 degrees.

Tricuspid Regurgitation – A disorder in which the heart’s tricuspid valve does not close tightly.

Trigeminal Nerve – The fifth cranial nerve, which carries sensory information from the face to the brain and controls motor functions for chewing.

Trochanter – One of two bony prominences near the proximal end of the thigh bone.

Trophoblast – The outer layer of cells of the blastocyst, which provides nutrients to the embryo and develops into a large part of the placenta.

Tubal Pregnancy – See ectopic pregnancy.

Tumor Necrosis Factor (TNF) – A cell signaling protein involved in systemic inflammation and is one of the cytokines that make up the acute phase reaction.

Tunica Vaginalis – A pouch of serous membrane that covers the testes.

Turbinate – A long, narrow, curled bone shelf that protrudes into the breathing passage of the nose.

Turner Syndrome – A chromosomal disorder affecting females where one of the X chromosomes is missing or partially missing.

Tympanic Membrane – The eardrum.

Type 1 Hypersensitivity – An allergic reaction provoked by re-exposure to a specific type of antigen referred to as an allergen.

Typhoid Fever – A bacterial infection that can spread throughout the body, affecting many organs.

Tyrosine – A non-essential amino acid that is a building block of protein.

Tetanus – A serious bacterial infection that causes painful muscle spasms and can lead to death.

Thalidomide – A medication once used as a sedative, now used to treat certain cancers and leprosy, and known for its historical association with birth defects.

Thiazide – A type of diuretic (water pill) used to treat high blood pressure by reducing the amount of fluid in the body.

Thoracic Outlet Syndrome – A group of disorders that occur when there is compression, injury, or irritation of nerves and/or blood vessels in the lower neck and upper chest area.

Thrombocytosis – A disorder in which your body produces too many platelets.

Thyrotoxicosis – An excessive concentration of thyroid hormones in the body.

---

U

Ulcer – A sore on the skin or a mucous membrane accompanied by the disintegration of tissue.

Ulcerative Colitis – A chronic, inflammatory bowel disease that causes inflammation in the digestive tract.

Ulna – The inner and longer of the two bones of the human forearm.

Ultrasound – A diagnostic imaging technique which uses high-frequency sound waves to create images of the inside of the body.

Umbilical Cord – A flexible cordlike structure containing blood vessels and attaching a human or other mammalian fetus to the placenta during gestation.

Unilateral – Pertaining to one side of the body.

Urea – A compound which is the end product of protein metabolism, present in the blood and urine.

Uremia – A condition involving abnormally high levels of waste products in the blood.

Ureter – The duct by which urine passes from the kidney to the bladder or cloaca.

Urethra – The duct through which urine is discharged from the bladder in most mammals and through which semen is discharged in males.

Urgency – A sudden, compelling need to urinate.

Urinalysis – A test of the urine used to detect and manage a wide range of disorders.

Urinary – Relating to urine or the organs of its passage.

Urinary Incontinence – The involuntary leakage of urine.

Urinary Tract Infection (UTI) – An infection in any part of the urinary system.

Urine – A liquid by-product of metabolism in humans and many animals.

Urology – A branch of medicine and physiology concerned with the function and disorders of the urinary system.

Urticaria – A condition characterized by red, itchy welts on the skin; also known as hives.

Uterine Fibroids – Noncancerous growths of the uterus that often appear during childbearing years.

Uterus – The organ in the lower body of a female where offspring are conceived and in which they gestate before birth; the womb.

UV Radiation – Ultraviolet radiation that is part of the electromagnetic spectrum and sunlight.

Uveitis – Inflammation of the uvea, the middle layer of the eye.

Ulceration – The process of forming ulcers.

Ulnar Deviation – A hand deformity that occurs when the fingers bend towards the ulna bone.

Umbilical Hernia – A hernia at the umbilicus (navel).

Upper Respiratory Infection – An infection that affects the nasal passages and throat.

Ureteral Stent – A thin tube inserted into the ureter to prevent or treat obstruction of the urine flow from the kidney.

Urethral Stricture – A narrowing of the urethra caused by injury or disease such as infection.

Urethritis – Inflammation of the urethra.

Uric Acid – A chemical created when the body breaks down substances called purines.

Urinary Bladder – The organ that collects urine excreted by the kidneys before disposal by urination.

Urinary Catheter – A tube placed in the body to drain and collect urine from the bladder.

Urinary Retention – The inability to completely or partially empty the bladder.

Urinary Stone – A stone formed anywhere in the urinary tract.

Urinary System – The organs of the body that produce, store, and discharge urine.

Urodynamic Testing – Tests that assess how well the bladder, sphincters, and urethra hold and release urine.

Urogenital – Pertaining to the urinary and genital organs.

Uropathy – Any disease of the urinary tract.

Urosepsis – Sepsis caused by a urinary tract infection.

Urostomy – A surgical procedure that creates a stoma (artificial opening) for the urinary system.

Uterine Cancer – Cancer that forms in the tissue of the uterus.

Uterine Prolapse – Occurs when the uterus sags or slips from its normal position into the vaginal canal.

Utilization Review – The process of ensuring healthcare services are used efficiently and appropriately.

Uveal Melanoma – A rare cancer of the eye involving the iris, ciliary body, or choroid (collectively known as the uvea).

Uvulitis – Inflammation of the uvula.

Ulnar Collateral Ligament Injury – An injury to the ligament on the inner side of the elbow.

Ultrasound Imaging – The use of ultrasonic waves to visualize subcutaneous body structures.

Unicompartmental Knee Arthroplasty – A type of knee surgery that replaces only the damaged or arthritic parts of the knee.

Universal Precautions – The infection control practice, mandated by OSHA, of treating all human blood and specified human body fluids as if they were known to be infectious for HIV, HBV, and other pathogens.

Unna Boot – A special gauze bandage used for the treatment of venous stasis ulcers and other venous insufficiencies of the leg.

Unstable Angina – A condition in which the heart does not receive enough blood flow and oxygen, leading to a risk of heart attack.

Upper GI Series – A group of x-ray tests that look at the upper part of the gastrointestinal tract.

Uricosuric Agents – Medications that increase the excretion of uric acid in the urine, used in the treatment of gout and hyperuricemia.

Urostomy Bag – A bag worn outside the body to collect urine after urostomy surgery.

Uterotonic – A substance that induces contraction or greater tonicity of the uterus.

Uvular Reflex – The gag or pharyngeal reflex, a reflex contraction of the back of the throat.

Uvulopalatopharyngoplasty – A type of surgery used to remove tissue and/or remodel tissue in the throat.

Ultrasound Therapy – The use of sound waves above the range of human hearing to treat injuries and to relieve pain.

Underweight – Weighing less than is normal, healthy, or required.

Undescended Testicle – A testicle that hasn’t moved into its proper position in the bag of skin hanging below the penis (scrotum) before birth.

Unifocal – Originating from or occurring at a single site.

Unit Dose – A premeasured amount of medication, as for administration at one time.

Universal Coverage – Health insurance coverage for all eligible residents of a political region and usually provided by government.

Unruptured Aneurysm – An aneurysm that has not burst.

Urea Breath Test – A diagnostic test for Helicobacter pylori involving the digestion of urea.

Uremic Frost – A dermatological condition that occurs due to an extreme increase in blood urea levels.

Uremic Pericarditis – Inflammation of the pericardium, the sac-like covering of the heart, which occurs in uremia.

Ureteroscopy – An examination of the upper urinary tract, usually performed with a ureteroscope that is passed through the urethra and bladder and then directly into the ureter.

Urethral Discharge – Discharge from the urethra, often seen in sexually transmitted infections.

Urethral Syndrome – Symptoms of urethritis and frequency of urination resembling those of a urinary tract infection but without positive urine culture.

Urethroplasty – Surgery performed to repair an injury or defect within the walls of the urethra.

Uric Acid Stones – Kidney stones formed from an accumulation of uric acid in the urinary tract.

Urinary Diversion – Surgical creation of a new route for urine and, sometimes, fecal waste after the bladder is removed.

Urinary Excretion – The process of removing waste and other non-useful materials from the body and eliminating them.

Urinary Frequency – Needing to urinate more often than usual.

Urinary Urgency – An immediate, strong urge to urinate that is hard to delay.

Urine Culture – A test to detect and identify organisms (usually bacteria) that may be causing a urinary tract infection.

Urine Dipstick Test – A basic diagnostic tool used to determine pathological changes in a patient’s urine.

Urodynamic Tests – Tests that assess how the bladder and urethra are performing their job of storing and releasing urine.

Urogenital Diaphragm – A layer of the pelvic floor that spans the area underneath the pelvis.

Urogenital System – The organ system of the reproductive organs and the urinary system.

Urography – Imaging of the urinary tract by x-rays using special dyes.

Urolithiasis – Formation of urinary calculi or stones in the kidneys or urinary tract.

Urologist – A physician who specializes in the study or treatment of the function and disorders of the urinary system.

Uropathy – Any disease of the urinary tract.

Urosepsis – Sepsis caused by a urinary tract infection.

Urticarial Rash – A kind of skin rash notable for pale red, raised, itchy bumps.

User Fee – A charge imposed by a government on people or organizations for the use of a particular public service.

Usher Syndrome – A relatively rare genetic disorder that is a leading cause of deafblindness.

Ustekinumab – A medication used to treat psoriasis and Crohn’s disease.

Uterine Atrophy – Thinning of the uterus walls.

Uterine Cancer – Cancer that forms in the tissue of the uterus.

Uterine Cavity – The space within the uterus.

Uterine Contraction – The tightening and shortening of the uterine muscles.

Uterine Cycle – The recurring reproductive cycle in females which involves changes in the lining of the uterus.

Uterine Fibroid – Benign tumors composed of muscle and fibrous tissue that develop in the uterus.

Uteroglobin – A steroid-inducible protein secreted by the mucosal glands of the uterus.

Utilitarianism – An ethical theory that determines right from wrong by focusing on outcomes.

UV Index – An international standard measurement of the strength of ultraviolet (UV) radiation from the sun at a particular place on a particular day.

Uvea – The middle layer of the eye that includes the iris, ciliary body, and choroid.

---

V

Vaccination – The administration of a vaccine to help the immune system develop protection from a disease.

Vagina – The muscular tube leading from the external genitals to the cervix of the uterus in women.

Vagal Response – A reflex where stimulation of the vagus nerve triggers a response that can include a decrease in heart rate and blood pressure.

Vagus Nerve – The tenth cranial nerve that innervates the digestive organs, heart, and other areas.

Valve – A structure in the heart or veins that maintains the flow of blood in one direction.

Varicella – Chickenpox; a disease caused by the varicella-zoster virus.

Varicose Veins – Gnarled, enlarged veins, most commonly appearing in the legs and feet.

Vascular – Relating to the blood vessels.

Vasculitis – Inflammation of the blood vessels.

Vasectomy – A surgical procedure for male sterilization or permanent contraception.

Vasoconstriction – The constriction of blood vessels, which increases blood pressure.

Vasodilation – The dilation of blood vessels, which decreases blood pressure.

Vasopressin – A hormone that acts to promote the retention of water by the kidneys and increase blood pressure.

Vector – An organism, typically a biting insect or tick, that transmits a disease or parasite from one animal or plant to another.

Vena Cava – A large vein carrying deoxygenated blood into the heart.

Venipuncture – The puncture of a vein as part of a medical procedure, typically to withdraw blood or administer medication.

Ventilation – The supply of air to the lungs, especially mechanically by means of a machine.

Ventricle – A hollow part or cavity in an organ, particularly one of the two lower chambers of the heart.

Ventricular Fibrillation – A severely abnormal heart rhythm that is life-threatening.

Ventricular Septal Defect (VSD) – A hole in the heart that is present at birth.

Vertebra – Each of the series of small bones forming the backbone.

Vertigo – A sensation of spinning dizziness.

Vesicle – A small fluid-filled bladder, sac, cyst, or vacuole within the body.

Vestibular System – The system in the body that is responsible for maintaining balance, posture, and the body’s orientation in space.

Viability – Ability of the fetus to survive outside the womb.

Viral Load – The number of virus particles in a particular volume of fluid; commonly used in reference to HIV.

Virulence – The severity or harmfulness of a disease or poison.

Virus – A small infectious agent that replicates only inside the living cells of other organisms.

Visceral – Pertaining to the internal organs in the main cavities of the body, especially those in the abdomen.

Visual Acuity – The clarity or sharpness of vision.

Visual Field – The total area in which objects can be seen in the peripheral vision while the eye is focused on a central point.

Vital Signs – Measurements of the body’s most basic functions; typically includes temperature, heart rate, blood pressure, and respiratory rate.

Vitamin – Any of a group of organic compounds that are essential for normal growth and nutrition and are required in small quantities in the diet because they cannot be synthesized by the body.

Vitreous Humor – The clear gel that fills the space between the lens and the retina of the eyeball.

Vocal Cords – Folds of tissue in the throat that are key in creating sounds through vocalization.

Voiding – Urination or defecation.

Volvulus – An obstruction caused by twisting of the stomach or intestine.

Vulva – The external female genitalia.

Vulnerable – Susceptible to physical or emotional attack or harm.

Vasovagal Syncope – A common cause of fainting, involving an overreaction of the body to certain triggers, such as the sight of blood or extreme emotional distress.

Vector-Borne Disease – An infection transmitted by the bite of an infected arthropod species, such as mosquitoes, ticks, or fleas.

Venous Thromboembolism (VTE) – A condition in which a blood clot forms most often in the deep veins of the leg and can travel in the circulation, lodging in the lungs.

Ventricular Tachycardia – A type of regular and fast heart rate that arises from improper electrical activity in the ventricles of the heart.

Vesicoureteral Reflux – A condition in which urine flows backward from the bladder into the ureters/kidneys.

Vestibular Neuritis – An inflammation of the vestibular nerve, a nerve in the ear that helps control balance.

Vitamin Deficiency – A shortage of a vitamin that can lead to health problems.

Vocal Fold Paralysis – A voice disorder that occurs when one or both of the vocal folds don’t open or close properly.

Volvulus of the Colon – A medical condition which involves a twist in the colon that can cause an obstruction.

Von Willebrand Disease – A lifelong bleeding disorder in which your blood doesn’t clot well.

Vasoactive Intestinal Peptide (VIP) – A peptide hormone that affects the secretion of intestinal juices, stimulates smooth muscle, and dilates peripheral blood vessels.

Vaginismus – A condition involving a muscle spasm in the pelvic floor muscles, which can make vaginal intercourse or any vaginal insertion painful or impossible.

Vagotomy – A surgical procedure that involves cutting the vagus nerve to reduce acid secretion in the stomach.

Valgus – Pertaining to or exhibiting an abnormal axial alignment in which the distal part of a limb is turned outward.

Valsalva Maneuver – A particular way of breathing that increases pressure in the chest, affecting the heart and blood flow.

Value-Based Care – A healthcare delivery model in which providers, including hospitals and physicians, are paid based on patient health outcomes.

Varicocele – An enlargement of the veins within the scrotum.

Vasculopathy – A disease affecting blood vessels.

Venography – An imaging test that uses an X-ray to show how blood flows through your veins.

Ventilator – A machine that supports breathing.

Ventriculography – An imaging test that uses X-rays to assess the heart’s ventricular function.

Verapamil – A medication used to treat high blood pressure and to control angina (chest pain).

Verruca – A wart.

Vertebral Column – The spine or backbone.

Vesicant – A chemical that causes extensive tissue damage and blistering on direct contact.

Vestibulocochlear Nerve – The eighth cranial nerve that transmits sound and equilibrium (balance) information from the inner ear to the brain.

Viability Scan – An ultrasound examination that is carried out usually between 6 and 10 weeks of pregnancy.

Vicarious Traumatization – A transformation in the self of a trauma worker or helper that results from empathic engagement with clients’ trauma experiences.

Videostroboscopy – A procedure that allows doctors to watch the motion of the vocal cords in slow motion.

Vigilance – The action or state of keeping careful watch for possible danger or difficulties, especially in a medical context.

Visceral Pain – Pain that results from the activation of nociceptors of the thoracic, pelvic, or abdominal viscera (organs).

Viscosupplementation – A medical procedure during which lubricating fluid is injected into a joint.

Visual Cortex – The part of the cerebral cortex that receives and processes sensory nerve impulses from the eyes.

Vitrectomy – A surgical procedure to remove some or all of the vitreous humor from the eye.

Vitreous Detachment – A common condition that occurs when the vitreous gel that fills the eye separates from the retina.

Vocal Hygiene – The practice of caring for the voice to prevent injury and hoarseness.

Volar – Pertaining to the palm of the hand or the sole of the foot.

Volunteer Bias – A type of bias that can occur in studies that rely on volunteers who may be different from the general population.

Vulvodynia – Chronic pain or discomfort around the opening of your vagina, for which there’s no identifiable cause and which lasts at least three months.

Vulvar Cancer – Cancer that occurs on the outer surface area of the female genitalia.

Vulvectomy – Surgical removal of all or part of the vulva.

V-Y Plasty – A surgical technique used to lengthen or reposition tissues.

Vaccine Efficacy – The percentage reduction of disease in a vaccinated group of people compared to an unvaccinated group.

Vacuolar Myelopathy – A condition where vacuoles form in the spinal cord, associated with HIV/AIDS.

Vagal Nerve Stimulation – A treatment that involves delivering electrical impulses to the vagus nerve.

Valvuloplasty – The repair or plastic surgery of a valve, especially of the heart.

Vancomycin – An antibiotic used to treat serious bacterial infections.

Vascular Dementia – A general term describing problems with reasoning, planning, judgment, memory, and other thought processes caused by brain damage from impaired blood flow to your brain.

Vascular Surgery – Surgery performed to treat diseases of the vascular system, including blood vessels.

Vasectomy Reversal – A surgery to undo a vasectomy.

Vasovagal Attack – A sudden drop in heart rate and blood pressure leading to fainting, often in reaction to a stressful trigger.

Vector Control – Methods to control or eliminate disease vectors.

Venous Insufficiency – A condition in which the veins have problems sending blood from the legs back to the heart.

Venous Ulcer – An open sore that results from poor blood flow in the veins of the legs.

Ventricular Assist Device (VAD) – A mechanical pump used to support heart function and blood flow in people with weakened hearts.

Ventricular Septum – The wall dividing the lower chambers of the heart.

Verbal Fluency Test – A psychological test aimed at evaluating a person’s ability to retrieve specific types of information within a time limit.

Vestibular Schwannoma – A benign tumor on the main nerve leading from the inner ear to the brain.

Veterinary Medicine – The branch of medicine that deals with the prevention, diagnosis, and treatment of disease, disorder, and injury in animals.

Vexatious Litigant – An individual who consistently brings litigation, regardless of its merit, to harass or subdue an adversary.

Viable Myocardium – Living heart muscle that has been injured and has reduced function but remains alive.

---

W

Wart – A small, hard, benign growth on the skin, caused by a virus.

Washout Period – A phase in a clinical trial where participants do not receive any treatment, allowing the effects of the previous treatment to dissipate.

Wasting Syndrome – Severe weight loss, muscle atrophy, fatigue, and weakness, often seen in patients with chronic diseases such as cancer or AIDS.

Water-Soluble Vitamins – Vitamins that can dissolve in water and are not stored in the body in significant amounts, needing regular supply in the diet.

Wax Block – A block of paraffin used in pathology to embed tissue specimens before slicing thin sections for microscopic examination.

Weaning – Gradually reducing a patient’s dependency on assisted breathing mechanisms or a baby from breastfeeding.

Weber Test – A quick screening test for hearing that involves placing a tuning fork on the center of the forehead.

Wedge Resection – Surgical removal of a triangular-shaped slice of tissue, often used in lung surgery.

Wegener’s Granulomatosis – A rare disease causing inflammation of the blood vessels, which restricts blood flow to various organs.

Weil’s Disease – A severe form of the bacterial infection leptospirosis.

Wernicke’s Area – A region of the brain important for language development.

Wernicke-Korsakoff Syndrome – A neurological disorder typically associated with chronic alcoholism and caused by thiamine (vitamin B1) deficiency.

Western Blot – A laboratory method used to detect specific protein molecules from among a mixture of proteins.

Wheal – A red, swollen mark left on flesh by a blow or pressure, often part of an allergic reaction.

Wheeze – A high-pitched whistling sound made while breathing, usually caused by a narrowing of the airways.

Whiplash – A neck injury due to forceful, rapid back-and-forth movement of the neck, like the cracking of a whip.

White Blood Cell (Leukocyte) – A cell in the blood that participates in the body’s immune system to fight infection.

White Coat Hypertension – A phenomenon in which patients exhibit elevated blood pressure in a clinical setting but not in other settings.

White Matter – The paler tissue of the brain and spinal cord, consisting mainly of nerve fibers with their myelin sheaths.

WHO (World Health Organization) – A specialized agency of the United Nations responsible for international public health.

Widal Test – A serological test for enteric fever or typhoid fever that checks for agglutinating antibodies.

Wilms’ Tumor – A rare kidney cancer that primarily affects children.

Wilson’s Disease – A genetic disorder that prevents the body from removing extra copper, leading to copper accumulation.

Withdrawal Symptoms – Symptoms that occur after stopping or reducing intake of a drug that has been used heavily over an extended period.

Wolff-Parkinson-White Syndrome – A condition in which there is an extra electrical pathway in the heart, leading to periods of rapid heart rate.

Womb – The uterus, the organ in women and female mammals in which embryos develop.

Wound Dehiscence – A surgical complication where a wound ruptures along a surgical incision.

Wound Granulation – The new vascular tissue that forms in the healing process of a wound.

Wrist Drop – A condition characterized by weakness of the wrist and fingers due to injury or nerve damage.

Wuchereria Bancrofti – A human parasitic worm that is the major cause of lymphatic filariasis.

Waardenburg Syndrome – A group of genetic conditions that can cause hearing loss and changes in coloring (pigmentation) of the hair, skin, and eyes.

Walk-In Clinic – A healthcare facility that accepts patients without an appointment and outside of the traditional emergency room.

Walker – A tool for aiding mobility, especially for the elderly and those recovering from injuries, providing support and stability.

Wallenberg’s Syndrome – A neurological condition caused by a stroke affecting the lateral medulla in the brainstem.

Wart Virus – Human papillomavirus (HPV), which causes warts on various parts of the body.

Water Brash – A sudden secretion of a large amount of saliva that is often stimulated by reflux.

Waterborne Diseases – Illnesses caused by microscopic organisms in contaminated water.

Watson’s Water Hammer Pulse – A medical sign consisting of a bounding and forceful pulse that rapidly collapses, associated with aortic regurgitation.

Weber’s Gland – Small mucous salivary glands located on the floor of the mouth.

Wedge Pressure – Pulmonary capillary wedge pressure, measured to evaluate left ventricular function.

Weight Management – Techniques and physiological processes that contribute to a person’s ability to attain and maintain a certain weight.

Welch Allyn – A company known for producing medical diagnostic devices, healthcare products, and medical equipment.

Wells Score – A clinical prediction rule for estimating the probability of deep vein thrombosis.

Wet Dressing – A therapeutic technique where a wet textile is applied to a wound or injury.

Wet Mount – A laboratory technique for observing specimens that are suspended in a liquid medium under the cover slip of a microscope slide.

Wheal and Flare Reaction – A rapid allergic response, characterized by a red lesion (wheal) surrounded by a red halo (flare).

Whipple’s Procedure – A complex operation to remove the head of the pancreas, the first part of the small intestine, the gallbladder and the bile duct.

White Blood Cell Count (WBC Count) – A test to measure the number of white blood cells in a volume of blood, used to detect infection or other diseases.

White Coat Syndrome – A phenomenon where a patient’s blood pressure is elevated during examination by a healthcare professional but not in other settings.

White Matter Lesions – Areas of damage to the white matter of the brain, seen in various diseases and conditions.

Whole Body Imaging – Techniques like MRI or CT scans that provide images of large portions or the entirety of the body.

Whole Exome Sequencing – A genomic technique for sequencing all of the protein-coding genes in a genome.

Whole Genome Sequencing – A process that involves determining the complete DNA sequence of an organism’s genome.

Widal Syndrome – A rare genetic condition affecting the development of the skin, hair, and immune system.

Williams Syndrome – A developmental disorder that affects many parts of the body, characterized by a unique personality, distinctive facial features, and intellectual disability.

Wilms Tumor Gene (WT1) – A gene that provides instructions for making a protein that is essential for the development of the kidneys and gonads.

Wing of Nose – The side part of the nose, known as the ala.

Wired Jaw – A treatment procedure where the jaws are wired shut to heal a fracture or correct deformities.

Wiskott-Aldrich Syndrome – A rare genetic disorder affecting the immune system and blood clotting.

Withholding Treatment – A decision not to initiate treatment or medical intervention for a patient.

Wolman Disease – A rare genetic disorder characterized by the buildup of fats in the cells of the adrenal glands, liver, and spleen.

Wolffian Duct – One of a pair of structures in the embryo that develop into male reproductive organs if male hormones are present.

Women’s Health – A branch of medicine that focuses on conditions and diseases that affect women’s physical and emotional well-being.

Wood’s Lamp Examination – A test that uses ultraviolet light to closely look at the skin.

Word Salad – A confused or unintelligible mixture of seemingly random words and phrases, most often used to describe a symptom of a neurological or mental disorder.

Work-Up – A thorough search including tests, consultations, and procedures used to identify a medical condition.

World Medical Association (WMA) – An international organization representing physicians, working to achieve the highest possible standards of medical care and ethics.

Wound Care – Management of the cleaning, dressing, and monitoring of both acute and chronic wounds to promote healing and prevent infection.

Wound Culture – A test to find and identify the microorganism causing an infection in a wound.

Wound Debridement – The medical removal of dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue.

Wrist Joint – The joint connecting the forearm to the hand.

Writer’s Cramp – A cramp or spasm affecting certain muscles of the hand and forearm, resulting from excessive use.

Writing Therapy – A form of expressive therapy that uses the act of writing and processing the written word as therapy.

Wry Neck – Also known as torticollis, a dystonic condition defined by an abnormal, asymmetrical head or neck position.

Wyburn-Mason Syndrome – A rare congenital disorder characterized by arteriovenous malformations in the retina, brain, and midface.

Waist-to-Hip Ratio – A measurement that compares the size of your waist in inches to your hips, used to assess the risk of cardiovascular disease.

Walker-Assisted Gait – Walking with the support of a walker to maintain balance and stability, typically used in rehabilitation settings.

Walking Pneumonia – A milder form of pneumonia that isn’t severe enough to require bed rest or hospitalization.

Warfarin – An anticoagulant medication used to prevent blood clots.

Wartenberg’s Sign – A neurological sign consistent with radial nerve palsy, marked by the inability to adduct the thumb.

Water Break – The rupture of the amniotic sac, which can occur naturally in the late stages of pregnancy or be induced medically.

Water Retention – Also known as fluid retention or edema, the buildup of fluid in the body’s tissues, most commonly in the ankles and feet.

Waterborne Pathogens – Microorganisms that are transmitted through contaminated water.

Watershed Stroke – A type of ischemic stroke that occurs due to the impairment of blood flow to a watershed area in the brain.

Wavefront Analysis – A diagnostic tool used in the field of ophthalmology to help improve optical quality and vision correction.

Weber’s Syndrome – A midbrain stroke syndrome involving the third cranial nerve and the cerebral peduncle.

Weight Bearing – The support weight of the body, often used in reference to walking or other lower extremity exercises.

Weight Cycling – The repeated loss and regain of body weight, also known as yo-yo dieting.

Well-Child Visit – Regular medical checkups for monitoring the growth and development of children.

Wheal-and-Flare Reaction – A skin response characterized by a wheal (a raised, red, and itchy area) surrounded by a flare of redness.

Wheelchair Accessible – Facilities or vehicles modified to accommodate individuals who use wheelchairs.

Whipple Disease – A rare bacterial infection that primarily affects the gastrointestinal system.

White Coat – A garment worn by physicians and other health care providers.

White Matter Disease – A disease that affects the white matter in the brain, often associated with aging, stroke, and Alzheimer’s disease.

Whole Grain – Grains and cereals that contain the entire grain kernel, including the bran, germ, and endosperm.

Whole-Person Care – A holistic approach to healthcare that addresses the full range of physical, emotional, mental, social, spiritual, and environmental influences that affect a person’s health.

Wild Type – The non-mutated form of a gene, found in nature.

Williams Syndrome – A rare genetic disorder characterized by mild to moderate intellectual disability or learning problems, unique personality characteristics, distinctive facial features, and heart and blood vessel (cardiovascular) problems.

Wilson’s Disease – A rare inherited disorder that causes copper to accumulate in the liver, brain, and other vital organs.

Wound Irrigation – The steady flow of a solution across an open wound surface to achieve wound hydration, to assist with the visual examination, and to remove deeper debris.

---

X

Xanthelasma – A flat or slightly raised yellowish deposit of cholesterol underneath the skin, usually on or around the eyelids.

Xanthoma – A condition in which fat builds up under the surface of the skin, causing yellowish bumps.

Xenograft – A surgical graft of tissue from one species to an unlike species (or genus or family).

Xenotransplantation – The transplantation of living cells, tissues, or organs from one species to another, such as from pigs to humans.

Xeroderma – Dry skin; a condition involving the integumentary system, which in most cases can safely be treated with emollients or moisturizers.

Xerophthalmia – A medical condition in which the eye fails to produce tears, causing dryness and potentially leading to corneal damage unless treated.

Xerostomia – Dry mouth or a decrease in the production of saliva.

Xiphoid Process – The smallest and lowest part of the sternum (breastbone).

X-linked – A mode of genetic inheritance by which a trait is carried on the X chromosome.

X-ray – A form of electromagnetic radiation that can pass through the body to produce images of internal structures, used in diagnostics.

Xylene – A volatile organic compound found in medical products, such as disinfectants and sterilization agents, used in histology labs.

Xylose – A sugar used in certain diagnostic tests to measure the absorption by the intestines.

XYZ Disease – A hypothetical or placeholder name often used in medical education to describe a case without identifying a specific disease, allowing for a focus on symptom-based learning.

Xerosis – A medical term for abnormally dry skin; this condition can be due to a variety of causes, including environmental and medical factors.

Xenodiagnosis – A diagnostic method used to detect the presence of an infectious agent by allowing a laboratory-bred vector to feed on the host and then examining the vector for the presence of the infecting organism.

Xenobiotic – A chemical substance found within an organism that is not naturally produced or expected to be present within the organism; often refers to drugs and pollutants.

X-Ray Diffraction – A technique used for identifying the atomic and molecular structure of a crystal, in which the crystalline atoms cause a beam of incident X-rays to diffract into many specific directions.

Xanthine – A substance found in the body that can lead to gout if produced in excess or if not adequately cleared by the kidneys.

Xanthochromia – The yellowish appearance of cerebrospinal fluid that indicates the presence of bilirubin, often seen in cases of subarachnoid hemorrhage.

X-linked Inheritance – A pattern of inheritance seen when a gene causing a disease or trait is located on the X chromosome, affecting predominantly males more than females.

---

Y

Yaws – A tropical infection of the skin, bones, and joints caused by the spirochete bacterium Treponema pertenue.

Yeast Infection – An infection caused by a fungus typically of the candida genus, manifesting as oral thrush, genital candidiasis, or skin infections.

Yellow Fever – A viral hemorrhagic disease transmitted by infected mosquitoes, characterized by fever, chills, severe headache, muscle pain, nausea, and potentially liver damage causing yellowing of the skin (jaundice).

Yeast – Fungi that are single-celled microorganisms which are part of the fungus kingdom, commonly known for their role in bread baking and alcohol brewing but also relevant in clinical infections.

Y-linked Genes – Genes that are found on the Y chromosome, typically concerning traits or disorders only affecting male individuals.

Yolk Sac – An extra-embryonic membrane that provides food (nutrition) via the blood vessels in the placenta to the embryo.

Yttrium-90 – A radioactive isotope used in certain types of radiation therapy to treat cancer, particularly useful in radioembolization.

Yoga Therapy – The use of yoga practices to improve health and treat medical conditions, focusing on posture, breathing, and meditation techniques.

Young’s Syndrome – A rare inherited disorder characterized by male infertility and damaged airways in the lungs, often associated with bronchiectasis.

Yips – A nervous disorder affecting athletes, particularly experienced by golfers, which causes them to twitch uncontrollably during their swing.

Y-chromosome Infertility – Problems with fertility in males attributed to genetic abnormalities in the Y chromosome.

Yolk Sac Tumor – A rare, malignant tumor of cells that line the yolk sac of the embryo, typically occurring in young children and infants.

Yield Point – In physiology, especially in biomechanics, the point at which a body moves from elastic deformation into plastic deformation.

Yogurt Consumption – Often discussed in medical contexts concerning its benefits for digestion and gut health due to the presence of probiotics.

Yawn – An involuntary action reflecting tiredness, stress, or the need to increase the body’s oxygen intake, sometimes used in medical assessments of neurological health.

Yellow Nail Syndrome – A rare condition characterized by yellow nails, lymphedema, and respiratory issues.

Yttrium – An element used in medicine in the form of yttrium-90 for radiation therapy, particularly for treating cancers.

Youth Health Services – Medical and psychological health services specifically targeted towards young people, addressing issues like sexual health, mental health, substance abuse, and nutrition.

YAG Laser – A type of laser used in various medical procedures, including eye surgeries, cosmetic skin treatments, and the removal of skin cancers.

Yo-Yo Dieting – The repeated loss and regain of body weight, also known as weight cycling, which can be harmful to health.

---

Z

Zidovudine – An antiretroviral medication used to prevent and treat HIV/AIDS.

Zika Virus – A mosquito-borne virus that can cause birth defects if a pregnant woman is infected.

Zinc Oxide – A compound used in various skin creams and ointments to treat diaper rash or sunburn.

Zollinger-Ellison Syndrome – A condition caused by tumors that lead to increased production of gastric acid, resulting in peptic ulcers.

Zygoma – The bone that forms the prominence of the cheek, also known as the cheekbone.

Zygote – The cell formed by the fusion of an egg and a sperm during fertilization.

Zoonosis – Any disease or infection that is naturally transmissible from vertebrate animals to humans.

Zoster – Another term for shingles, a reactivation of the chickenpox virus in the body, causing a painful rash.

Zinc Deficiency – A lack of zinc which can lead to hair loss, diarrhea, and a compromised immune system.

Zygomatic Arch – The bone arch that forms the prominence of the cheek; part of the temporal and zygomatic bones.

Zinc Supplement – A dietary supplement used to prevent or treat zinc deficiency.

Ziehl-Neelsen stain – A special bacteriological stain used to identify acid-fast organisms, mainly Mycobacteria.

Zoonotic Pathogens – Pathogens that are transmitted from animals to humans.

Zenker’s Diverticulum – A condition in which a pouch develops in the throat at the junction of the esophagus and throat, causing swallowing difficulties.

Zeta Potential – A scientific term used in medicine and biology to refer to the electrokinetic potential in colloidal dispersions.

Zero-Order Kinetics – A situation in drug kinetics where the rate of drug elimination is constant regardless of the concentration of the drug.

Zygomatic Fracture – A break in the zygomatic bone, one of the facial bones, typically due to trauma.

Zollinger-Ellison Test – Diagnostic tests used to diagnose Zollinger-Ellison Syndrome, including measuring levels of gastric acid and hormones.

Zinc Finger – A small protein structural motif that is characterized by the coordination of one or more zinc ions in order to stabilize the fold.

Zygomatic Complex – The part of the skull that provides the prominences of the cheeks and forms the lateral walls and floors of the orbits.

Zone of Inhibition – In microbiology, a region where bacterial growth is inhibited around a substance in a culture plate.

Zooplankton – Small and often microscopic aquatic animals that are a key source of food for many marine species and are used in studies on environmental health.

Zygomaticus – A facial muscle that draws the upper lip upward and outward, used in smiling.

Zymogen Granule – A structure in some cells that stores proenzymes, which are precursors to enzymes.

Ziehl-Neelsen Technique – A laboratory technique for staining certain types of bacteria, important for diagnosing diseases like tuberculosis.

 

 

 

 

 

 

---