Dictionary

Enter a word or phrase below to search our online dictionary of over 1,300 general medical terms, or click on a letter of the alphabet to view all terms beginning with that letter:

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Phrase Definition
bacteremia The presence of bacteria in the blood.
bacteria Single-celled microorganisms with one of three basic shapes: rod-like (bacilli), spherical (cocci) and spiral (spirilla). Bacteria are commonly thought of as disease-causing agents. But many bacteria are beneficial and don't cause disease.
bacteriuria The presence of bacteria in the urine.
Baker's cyst A swelling of the knee caused by an escape of fluid from a sac behind the knee.
ballism Quick, jerking movements that occur in people with chorea.
barium A chalky substance used in x-ray studies of the digestive tract to highlight abnormalities.
barotrauma Injury caused by pressure differences between the atmosphere and the air-filled spaces in the body. The most common of these injuries are the ear and sinus blocks that can occur during air travel.
Bartholin cyst A cyst caused by an infection of the glands on the vaginal wall.
BCG (bacille Calmette-Guerin) vaccine A vaccine that offers some protection against tuberculosis. It's now rarely used in the U.S. because it doesn't give total protection.
bedsore An ulcer caused by chafing or by the pressure of the body against the bed.
Bell's palsy A usually temporary loss of feeling or movement of the face, usually on one side, causing an inability to close the eye or mouth on that side.
bends A condition that results from rapidly decreasing atmospheric pressure on the body. Symptoms include joint pain, chest pain, shortness of breath and coma. The condition may be fatal.
benign A nonlife-threatening condition. Not malignant. Not cancerous.
benign familial tremor An inherited disorder that causes a slow tremor in the hands, head and voice. It may affect only one side of the body, be worse when moving than when resting and worsen with age.
beriberi A deficiency disease caused by dietary insufficiency of vitamin B1 (thiamine). Symptoms include general weakness and painful rigidity.
biceps A muscle having two heads. The most familiar is the large muscle in the front of the upper arm responsible for flexing the forearm.
bicuspid A tooth named for the two-pointed projections on the crown.
bifocals Eyeglasses with divided lenses. The two parts of each lens have different strengths, allowing the wearer to focus the eye for either near or distant vision.
bile A clear yellow fluid produced by the liver and stored in the gallbladder. Aids in digestion.
bilirubin A pigment produced in the liver by the breakdown of hemoglobin from old red blood cells. Bilirubin is normally eliminated in the bile. A variety of diseases may cause bilirubin to collect in the body, resulting in a yellow discoloration of the skin known as jaundice.
binocular Using both eyes at the same time. Binocular vision is the most important element of depth perception.
biopsy Removal and exam of a tissue sample taken from a living body. This procedure helps determine if the tissue is cancerous.
bipolar affective disorder A psychiatric disorder in which the affected person has both depressed and happy, energetic (manic) episodes. This is a newer term for manic-depressive disorder.
blackhead A dark-topped plug of fatty material in the opening of a hair follicle. The color is the result of exposure of the fat to the air.
blackout 1. Short-term loss of vision and consciousness. 2. In an alcoholic person, loss of memory for a period of time.
bladder The organ that temporarily stores a substance. Commonly used in reference to the urinary bladder, which holds urine until it's eliminated.
blepharitis Inflammation of the eyelid.
blepharoplasty Plastic surgery on the eyelid.
blindness Loss of vision. Legally, visual acuity less than 20/200 with glasses.
blister Buildup of watery or bloody fluid under the skin.
blood The fluid circulating through the heart, arteries and veins. Blood is responsible for transporting oxygen to body tissues, carrying waste products away from the tissues and delivering a wide variety of biochemical substances throughout the body to main.
blood poisoning Infection within the circulatory system. A potentially life-threatening condition that requires prompt treatment.
blood pressure The pressure exerted by the blood against the walls of the blood vessels.
boil A skin infection characterized by a localized buildup of pus.
bone marrow The tissue within the cavity of the bones where new blood cells are made.
Borrelia A class of disease-causing bacteria that includes the organisms that cause relapsing fever and Lyme disease.
botulism An extremely dangerous form of food poisoning caused by the toxin of Clostridium botulinum.
bovine Having to do with cattle. For example, bovine insulin is insulin obtained from cattle.
bowel See intestine.
Bowen's disease A precancerous skin condition that first appears as psoriasis-like scaling.
bowleg A deformity of the legs in which the space between the knees is greater than normal.
brace A device used to support a body part, correct or prevent deformities, or control movement.
bradycardia Slow heart rate and pulse, usually slower than 60 beats per minute.
Braxton Hicks contractions Contractions of the uterus during pregnancy that are sometimes mistaken for labor. Also called false labor.
breasts Milk-secreting glands protruding from the upper front part of a woman's body.
breech birth A birth in which the feet or buttocks of the baby appear first through the birth canal.
bridge A structure that joins two parts. For example, a dental bridge contains artificial teeth and joins the natural teeth at either end.
Bright's disease Nephritis. A group of kidney diseases manifested by albumin in the urine and edema (swelling).
bronchi The tubular passages, also called bronchial tubes, that carry air into the lungs.
bronchiolitis An infection of the bronchioles, the tiny air tubes in the lungs.
bronchitis Inflammation of the bronchi.
bronchospasm Contraction of the muscle in the walls of the bronchi.
bronze diabetes A disorder of iron metabolism resulting in iron pigment deposits in the skin and other body tissues that causes a change in skin color.
brucellosis An infection characterized by fluctuating fever, headache, anemia and vague physical discomfort that's transmitted to humans from domesticated goats, pigs and cattle.
bruise Discoloration of the skin due to a buildup of blood in the underlying soft tissues. Also called a contusion.
bruxism Grinding of the teeth.
bubo A swollen, infected lymph node (especially in the groin). The node may enlarge enough that it begins to drain through the skin.
Buerger's disease Blockage of medium-sized blood vessels in the hands and feet by clotting and inflammation. This process causes severe pain and may lead to gangrene.
bulimia An eating disorder characterized by binge eating followed by vomiting or use of laxatives. Usually caused by a variety of psychological reasons.
bunion Localized swelling of the big toe at its joint with the foot.
bursa A small, fluid-filled sac that allows one part of a joint to move freely over another part.
bursitis Inflammation of a bursa.