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


Filter By Alphabet
All terms
  • orgasm

    Sexual climax.

  • organic

    Having to do with substances derived from living organisms.

  • organ

    A structural unit of an animal or plant that serves a specific function.

  • orchiectomy

    The surgical removal of one or both testicles. Also called castration.

  • orbit

    The bony cavity containing the eyeball. Eye socket.

  • optometry

    The practice of eye and vision care.

  • optical

    Having to do with vision.

  • optic neuritis

    Inflammation of the optic nerve, which connects the eye to the brain. Symptoms include pain with eye movement, blurred vision…

  • ophthalmology

    The branch of medicine that pertains to the eye and its diseases.

  • oophorectomy

    The surgical removal of an ovary.

  • oncology

    The study of tumors.

  • oliguria

    A condition characterized by an abnormally small output of urine.

  • oligospermia

    A low number of sperm in the semen.

  • oligomenorrhea

    Light menstrual flow.

  • olfactory

    Having to do with the sense of smell.

  • olecranon

    The projection of the ulna (the larger of the two bones in the forearm) at the elbow.

  • odontalgia


  • ocular

    Having to do with the eye.

  • occupational therapy

    Teaching useful skills to sick or handicapped people to promote rehabilitation and healing.

  • occupational illness

    Any illness caused or aggravated by a person’s job.

  • occult

    Hidden from view.