Dictionary of Medical Terms

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 A
  • antibody

    A protein produced by the body to neutralize an invading foreign agent or antigen, such as a virus.

  • antidote

    An agent used to counteract a poison.

  • antigen

    A foreign agent capable of starting an immune response or causing the body to produce antibodies.

  • antiserum

    A serum that contains antibodies. Serum from a person or animal with immunity to a certain disease can, in some…

  • anus

    The opening of the rectum.

  • anxiety

    A feeling of nervousness, uneasiness, apprehension or dread.

  • aorta

    The large artery that carries blood from the heart to the rest of body.

  • apathy

    Lack of emotions.

  • Apgar score

    A scoring method from zero to 10 for describing the health of an infant at birth, based on heart rate,…

  • aphagia

    Inability to swallow.

  • aphasia

    A partial or total loss of the power to use or understand words.

  • aphthous ulcers

    A painful sore in the mouth. Also called a canker sore.

  • apnea

    Temporary pause in breathing.

  • appendectomy

    Surgical removal of the appendix.

  • appendix

    A finger-like appendage near the junction of the large intestine and the small intestine.

  • areola

    The dark area of the breast surrounding the nipple.

  • arteriosclerosis

    Commonly called “hardening of the arteries.” An abnormal thickening and loss of elasticity of the wall of the arteries.

  • arteriovenous malformation

    Abnormal group of dilated blood vessels, most often occurring in the brain.

  • artery

    A vessel that carries blood away from the heart to various parts of the body.

  • arthralgia

    Pain in a joint.

  • arthritis

    Inflammation of a joint.