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 I
  • indigestion

    Upper abdominal discomfort usually experienced after a meal due to incomplete digestion.

  • induration

    The process of hardening. An abnormally hard spot.

  • infarct

    An area of dead or dying tissue produced by lack of blood flow to or from that area. For example,…

  • infection

    Causing disease, especially by the presence of foreign microorganisms in the body, including bacteria, viruses or parasites.

  • infectious disease

    A disease that can be spread from one person to another.

  • infertility

    Inability to produce children.

  • inflammation

    Swelling, redness, warmth and pain. A body tissue’s protective response to injury.

  • influenza

    A contagious and infectious respiratory illness usually occurring in the winter.

  • ingrown nail

    Edges of the nail become trapped under the skin, causing inflammation and, sometimes, infection.

  • injection

    A fluid introduced into the body by a syringe and needle.

  • innate

    Inborn, hereditary.

  • inoculation

    The injection of a disease agent into the body to cause a mild form of the disease and build…

  • inoperable

    Not curable through surgery.

  • insanity

    Any form or degree of mental disturbance or unsoundness of mind, permanent or temporary, that makes a person incapable of…

  • insemination

    To deposit sperm in the vagina.

  • insomnia

    An inability to fall asleep or to remain asleep.

  • insulin

    The hormone produced by the pancreas for regulating carbohydrate metabolism. Used in the treatment of diabetes mellitus.

  • integument


  • intercourse

    The exchange of communication between individuals. Sexual intercourse is the sexual joining of two people; coitus.

  • intestine

    The tube involved in digestion and extending from the stomach to the anus. Consists of the small intestine and the…

  • intoxication

    Poisoning, or the state of being affected by a poisonous substance. Often used to describe drunkenness.