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

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  • 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 brain from injury, disease, or alcohol or other chronic drug abuse.

  • 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 variety of potentially life-threatening ailments.

  • anaerobic exercise

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

  • anaphylaxis

    The most severe form of allergy, in which the person's heart and lungs are unable to keep working, and death occurs unless prompt medical attention is obtained.

  • 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 the red blood cells.

  • 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 increases in size, the sac tends to become thinner, and the risk of its breaking becomes greater.

  • 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 reasons.

  • anosmia

    Loss of the sense of smell.

  • antepartum

    Occurring before delivery of a baby.