Medical Glossary

Picture of Medical Glossary
Medical Glossary provides definitions for the most common medical terms. It contains easy-to-understand explanations of medical terms.


Abdomen - Area between the chest and the hips that contains the stomach, small intestine, large intestine, liver, gallbladder, pancreas, and spleen.

Absorption - The way substances pass into tissue as nutrients from food move from the small intestine into the cells of the body.

Abutment teeth - The surrounding teeth of each side of the gap where teeth are missing

Acquired deafness - Loss of hearing that occurs or develops over the course of a lifetime; deafness not present at birth.

Adenocarcinoma - A cancer that develops in the lining or inner surface of an organ.

Agonist - A drug capable of combining with receptors to initiate an action that can be known in advance.

Amenorrhea - Absence or cessation of menstrual periods.

Anal fistula - Channel that develops between the anus and the skin. Most fistulas are the result of an abscess (infection) that spreads to the skin

Anesthesia - Loss of feeling or sensation as a result of drugs or gases. General anesthesia causes loss of consciousness; local or regional anesthesia causes loss of feeling only to a specified area.

Antacids - Medicines that balance acids and gas in the stomach.

Antibiotic - Chemical substances, produced by living organisms or synthesized (created) in laboratories, for the purpose of killing other organisms that cause disease.

Antioxidants - Compounds that protect against cell damage inflicted by molecules called oxygen-free radicals, which are a major cause of disease and aging.

Anus - Opening at the end of the digestive tract where bowel contents leave the body.

Anemia - A condition in which the number of red blood cells is below normal.

Aorta - Blood vessel that delivers oxygen-rich blood from the left ventricle to the body; it is the largest blood vessel in the body.

Areola - Dark area of skin that surrounds the nipple of the breast.

Artificial ventilation - The process of supporting breathing by manual or mechanical means when normal breathing is inefficient or has stopped

Axon - The long, hair like extension of a nerve cell that carries a message to a nearby nerve cell.


Bladder - A hollow organ that urine drains into from the kidneys.

Body mass index (BMI) - A number, derived by using height and weight measurements, that gives a general indication of whether or not weight falls within a healthy range.

Bowel - Another word for the small and large intestines.

Breast conservation therapy - Surgery to remove a breast cancer and a small amount of benign tissue around the cancer without removing any other part of the breast. This procedure is also called lumpectomy, segmental excision, limited breast surgery.

Breast implant - A manufactured sac that is filled with silicone gel (a synthetic material) or saline (sterile saltwater); the sac is surgically inserted to increase breast size or restore the contour of a breast after mastectomy.

Breast reconstruction - Surgery to rebuild a breast mound after mastectomy.

Baldness - Baldness can be localized to the front and top of the head, such as in male pattern baldness; patchy, such as in alopecia areata; or involve the entire head, such as in alopecia capitis totalis.

BCG - Bacille Calmette-Guerin is an inactivated form of the bacteria that activates the immune system when injected and gives immunity against the tuberculosis disease.

Bacterial infection - An infection caused by bacteria (micro-organisms which attack the immune system). Bacterial infections can be treated with antibiotics.


CA-125 test - Blood test to detect an elevated level of a protein antigen called CA-125, which may indicate ovarian cancer, among other disorders.

Calculi - Stones or solid lumps such as gallstones.

Cancer - Abnormal cells that divide without control, which can invade nearby tissues or spread through the bloodstream and lymphatic system to other parts of the body.

Cardiac - Pertaining to the heart.

Circulatory system - Pertaining to the heart and blood vessels, and the circulation of blood

Colon - large intestine

Colostrum - Thin, white, first milk produced by the breasts during late pregnancy and for a few days after childbirth. It provides a nursing infant with essential nutrients and infection-fighting antibodies.

Crown - A "cap" that covers a cracked or broken tooth, unfixed by a filling, to approximate its normal size and shape.

Cryptosporidia - Parasite that can cause gastrointestinal infection and diarrhea

Cancer - A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread through the bloodstream and lymphatic system to other parts of the body.

Calculus - Accumulation of mineral salts in various parts of the body, such as a kidney stone or on teeth.


Deciduous teeth - Also known as "baby" or primary teeth.

Delusions - A condition in which the patient has lost touch with reality and experiences hallucinations and misperceptions.

Dendrite - A thread-like extension from a nerve cell that serves as an antenna to receive messages from the axons of other nerve cells.

Dental implants - Small dental appliances that are inserted into the upper and lower jaws to help restore a mouth that has little or no non-restorable teeth

Diaphragm - Primary muscle used for respiration, located just below the lung bases.

Dacarbazine - An anticancer drug that belongs to the family of drugs called alkylating agents.

Dactinomycin - An anticancer drug that belongs to the family of drugs called antitumor antibiotics

Danazol - A synthetic hormone that belongs to the family of drugs called androgens and is used to treat endometriosis. It is being evaluated in the treatment of endometrial cancer.

Daunorubicin - An anticancer drug that belongs to the family of drugs called antitumor antibiotics.


Echocardiography - A procedure that uses ultrasonic waves directed over the chest wall to obtain a graphic record of the heart's position, motion of the walls, or internal parts such as the valves.

Ectopic pregnancy - Pregnancy occurring in an abnormal position outside the uterus

Eclampsia - Seizures due to high blood pressure during pregnancy.

Erection - Is the hardening, enlarging and rising of the penis which often occurs in the sexually aroused male.

Ejaculation - Sudden discharge of seminal fluid from the penis during sexual intercourse, masturbation, or sexual climax.

Endometrium - Mucous membrane lining of the inner surface of the uterus that grows during each menstrual cycle and is shed in menstrual blood.

Enteroscopy - Examination of the small intestine with an endoscope

Extrinsic asthma - Asthma that is triggered by an allergic reaction - usually to something that is inhaled.


Fallopian tubes - Two thin tubes that extend from each side of the uterus, toward the ovaries, as a passageway for eggs and sperm

Fibrocystic breasts - Non-cancerous condition in which small lumps and cysts develop in the breasts.

Food intolerance - An adverse food-induced reaction that does not involve the immune system

Fetus - The name used for the unborn baby from the end of the 8th week after conception

False labor - Irregular pains and contractions that give a pregnant woman the illusion that labor has begun.

Far sightedness - This is a refractory error where the eyeball is too short and the light focuses behind the retina of the eye. This leads to difficulty in focusing on objects that are close to the eye. It is also called hyperopia or hypermetropia or colloquially as farcing

Fatty Acids - A major component of fats that are used by the body for energy and tissue development.


Galactose - A type of sugar found in milk products and sugar beets, it is also made by the body. It is considered a nutritive sweetener because it has calories.

Gallbladder - The pear-shaped organ that sits below the liver. Bile is concentrated and stored in the gallbladder.

Gamma rays - High-energy rays that come from a radioactive source such as cobalt-60

Gastric - Pertaining to the stomach

Gastric ulcer - An open sore on the lining of the stomach

Gastroenterologist - A doctor who specializes in diagnosing and treating disorders of the digestive system.

Genital herpes - A sexually transmitted disease caused by the herpes simplex virus.

Glycogen - Converted glucose for storage. Glycogen plays a role in controlling blood sugar levels.

Gray matter - The darker-colored tissues of the central nervous system; in the brain, the gray matter includes the cerebral cortex, the thalamus, the basal ganglia, and the outer layers of the cerebellum.

Gustation - Act or sensation of tasting.


Halitosis - An oral health condition characterized by consistently odorous breath.

Hepatitis E - Virus spread mostly through unclean water.

Hypothalamus - Small structure at the base of the brain that regulates many body functions, including appetite and body temperature.

Hysteroscope - Visual examination of the canal of the cervix and the interior of the uterus using a viewing instrument inserted through the vagina.

Haemoglobinuria - The presence of free hemoglobin in the urine.

Hay fever - The popular name for runny nose or allergic rhinitis is an allergic reaction of the immune system upon exposure to foreign substances

Hb - Hemoglobin


Immobilization - Preventing movement to allow for natural healing to take place.

Immune system - Complex network of specialized cells and organs that work together to defend the body against attacks by "foreign" invaders such as bacteria and viruses

In vitro fertilization (IVF) - Treatment for infertility in which a woman's egg is fertilized, outside her body, with her partner's sperm or sperm from a donor.

Inflammatory bowel disease (IBD) - Long-lasting problems that cause irritation and ulcers in the gastrointestinal (GI) tract - the most common disorders are ulcerative colitis and Crohn's disease.

Isometric - Muscle contraction without movement at the joint.


Jaundice - Symptom of liver damage, bile obstruction or excessive red-blood-cell destruction. Jaundice is characterized by yellowing of the whites of the eyes, yellow skin, dark urine and light stool.

Jordan frame - Specialized stretcher developed for transport of patients with a suspected spinal injury.

Jumper's knee - Associated with a small area of degeneration of the tendon attachment at the lower pole of the patella (knee-cap), characterized by pain and extreme local tenderness.


Ketoacidosis - High blood glucose, often caused by illness or taking too little insulin.

Knee reconstruction - Surgical restoration of biomechanics of the knee


Labor - Periodic rhythmical contraction of the uterus which opens the cervix and leads to the birth of a baby.

Lactase - Enzyme that helps body convert lactose to glucose and galactose.

Lactation - The production of breast milk.

Laparoscopy - Examination of the peritoneum through a lighted instrument.


Malignant tumor - A mass of cancer cells that may invade surrounding tissues or spread to distant areas of the body.

Mallet finger - Common condition due to the rupture of the long extensor tendon of the finger.

Mammogram - A low-dose x-ray of the breast.

Miscarriage - Spontaneous termination of a pregnancy before the fetus has developed enough to survive outside the uterus.

Mucus - Clear liquid made by the intestines that coats and protects tissues in the gastrointestinal tract.

Myopia - Nearsightedness.

Malabsorption - Poor absorption of nutrients from the intestinal tract into the bloodstream.

Malignant tumor - A tumor made up of cancer cells of the type that can spread to other parts of the body.


Nasal - By or having to do with the nose.

Natal - Pertaining to birth.

Narcotic - Depresses the central nervous system, reduces pain and may cause drowsiness and euphoria. Narcotics are NOT addictive when taken for pain.

Nausea - Vomiting sensation.


Ovaries - Pair of small glands, located on either side of the uterus, in which egg cells develop and are stored, and the female sex hormones estrogen and progesterone are produced.

Ovulation - Release of a mature egg from an ovary.

Obesity - Over weight

Occult - Obscure; hard to detect

Ocular - Pertaining to the eye


Pancreas - Long gland that lies behind the stomach; manufactures insulin and digestive enzymes.

Pepsin - Enzyme made in the stomach that breaks down proteins.

Peptic ulcer - Sore in the lining of the stomach usually caused by the bacterium

Plantar warts - Warts that occur on the sole of the foot and look like calluses; often a result of an infection or a specific virus

Portal hypertension - Abnormally high blood pressure in the portal vein, which supplies the liver with blood from the intestine

Prostatitis - Inflamed conditions of the prostate gland that may be accompanied by discomfort, pain, frequent urination, infrequent urination, and, sometimes, fever.

Pupil - the dark center in the middle of the iris through which light passes to the back of the eye

Paget's cells - Extensively proliferating cancerous epithelial cells seen in the epidermis

Palate - The roof of the mouth. The front portion is bony (hard palate), and the back portion is muscular (soft palate).

Palpebral fissures - The gap between the upper and lower eyelids.

Pancreas - A glandular organ located in the abdomen. It makes pancreatic juices, which contain enzymes, which aid in digestion. It produces several hormones, including insulin. The pancreas is surrounded by the stomach, intestines, and other organs.

Pap smear - A test to detect cancer of the cervix.


Quadriceps - Large muscles located on the front of each thigh.


Rheumatic fever - Is a childhood disease that may damage the heart valves or the outer lining of the heart.

Rhinitis - Is an inflammation of the mucous membrane that lines the nose; often due to allergy to pollen, dust, or other airborne substances; causes sneezing, itching, a runny nose, and nasal congestion.

Rupture - Break or tear in any organ or soft tissue.


Spasm - A condition in which a muscle or group of muscles involuntarily contract.

Saliva - The watery fluid secreted into the mouth by the salivary glands that are in the mouth. It keeps the mouth moist, lubricates food to aid in swallowing, makes it possible to taste food, and contains digestive enzyme

Scar - A mark in the skin made by a wound or ulcer, which remains after the healing process, is complete.

Saturated fat - A type of fat that comes from animals

Saline - A solution of salt and water.


Temporal arteries - Vessels located over the temples on each side of the head that supply blood to part of the head.

Thrombolysis - The breaking up of a blood clot.

Tyrosine - The amino acid from which dopamine is made.

Tartar - White or yellowish deposit on the margin of the teeth.

Tay - Sachs disease - A recessive genetic disorder common among Ashkenazi Jews in which the enzyme needed to break down certain lipids is absent.


Ulcer - Sore on the skin surface or on the stomach lining.

Ureters - Two tubes that carry urine from the kidneys to the bladder.

Urethra - Narrow channel through which urine passes from the bladder out of the body.

Urinary retention - The inability to empty the bladder.

Uterus (Also called the womb.) - The uterus is a hollow, pear-shaped organ located in a woman's lower abdomen, between the bladder and the rectum, that sheds its lining each month during menstruation and in which a fertilized egg implants and grows into a fetus.


Vaccination - Injection of a vaccine to create immunity.

Vagina - The passage (birth canal) connecting the female external genitalia with the uterus.

Vaginal discharge - Flow of fluid from the vagina

Vaginitis - An infection of the vagina usually caused by a fungus. A woman with this condition may have itching or burning and may notice a discharge.

Vaporizer - A machine that adds moisture to the air to prevent dryness in the mouth, nose, and throat. Vaporizers typically put out hot steam.

Vascular - Pertaining to blood vessels (arteries, veins, and capillaries).

Vitrectomy - An operation to remove the blood that sometimes collects at the back of the eyes when a person has eye disease.

Volvulus - Twisting of the stomach or large intestine.

Vomiting - Release of stomach contents through the mouth.


Wart - A raised growth on the surface of the skin or other organ.

Water-soluble - Dissolves in water.

Wax - High-molecular-weight hydrocarbons; they are insoluble in water.


Xerostomia - a dry mouth condition; can be caused by a number of things, including rheumatoid arthritis, diabetes, kidney failure, infection with HIV (the virus that causes AIDS), drugs used to treat depression, and radiation treatment for mouth or throat cancer.

Xanthomas - Are deposits of fatty materials under the surface of the skin ranging in size from very small to more than 3 inches in diameter.


Yasargil clip - A particular design of device for occluding the neck of a cerebral aneurysm.


Zenker's diverticulum - Pouches in the esophagus from increased pressure in and around the esophagus.