Gain a better understanding of medical terminology by searching our dictionary of more than 1,300 terms.


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All terms that start with the letter B
  • 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…

  • 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…

  • 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…

  • 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…

  • bends

    A condition that results from rapidly decreasing atmospheric pressure on the body. Symptoms include joint pain, chest pain, shortness of…

  • 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…

  • 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…

  • 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…

  • 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…

  • binocular

    Using both eyes at the same time. Binocular vision is the most important element of depth perception.