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
  • ambulatory

    Able to walk. Not confined to bed.

  • amenorrhea

    Absence of menstrual periods.

  • amnesia

    Partial or total loss of memory, usually as the result of psychological trauma or stress, or physical damage to the…

  • amnion

    The membrane enclosing a developing fetus; it’s filled with a protective liquid called amniotic fluid.

  • amputation

    The surgical removal of a limb or other appendage because of damage by trauma or as a treatment for a…

  • anaerobic exercise

    Brief, intense exercise that leads to an oxygen debt in a certain area of tissue. Weight lifting is an…

  • anaphylaxis

    The most severe form of allergy, in which the person’s heart and lungs are unable to keep working, and death…

  • androgen

    Any substance that produces male characteristics. Testosterone and androsterone are natural androgens.

  • anemia

    A decreased ability of the blood to carry oxygen because of a reduction in either the number or quality of…

  • anesthesia

    Drug-induced loss of feeling or sensation.

  • anesthetic

    An agent used to produce anesthesia.

  • aneurysm

    A thin sac caused by a weakened area in the walls of blood vessels or the heart. As an aneurysm…

  • angina pectoris

    Chest pain caused by decreased oxygen delivery to the heart muscle.

  • angioma

    A noncancerous tumor made up of many blood vessels.

  • anhidrosis

    Absence of sweating. An inability to sweat greatly interferes with the body’s ability to control its internal temperature.

  • ankylosis

    Abnormal stiffening of a joint.

  • anomaly

    Deviation from normal.

  • anorchism

    Congenital absence of both testes.

  • anorexia nervosa

    An eating disorder manifested primarily by a loss of desire or willingness to eat for a variety of psychological…

  • anosmia

    Loss of the sense of smell.

  • antepartum

    Occurring before delivery of a baby.