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Glossary

Showing 851-860 out of 1156 Terms

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  • Oncologist

    (on-KAH-loh-jist)

    A doctor who has special training in diagnosing and treating cancer. Some oncologists specialize in a particular type of cancer treatment. For example, a radiation oncologist specializes in treating cancer with radiation.

  • Oncology

    on-KAH-loh-jee

    A branch of medicine that specializes in the diagnosis and treatment of cancer.

  • Operating room

    Surgical site.

  • Ophthalmologist

    OF-thul-MAH-loh-jist

    A doctor who has special training in diagnosing and treating eye problems, including injury and disease.

  • Opioid

    (OH-pee-OYD)

    A substance used to treat moderate to severe pain. Opioids are like opiates, such as morphine and codeine, but are not made from opium. Opioids bind to opioid receptors in the central nervous system. Opioids used to be called narcotics. An opioid is a type of alkaloid.

  • Optic nerve

    (OP-tik nerv)

    The nerve that carries messages from the retina to the brain.

  • Optical

    Pertaining to the sense of sight or to the eyes.

  • Organ

    (OR-gun)

    A part of the body that performs a specific function. For example, the heart is an organ. organelle.

  • Organism

    (OR-guh-NIH-zum)

    A living thing, such as an animal, a plant, a bacterium, or a fungus.

  • Orgasm

    (OR-ga-zum)

    The final part of the sex act, which involves contraction of sexual organs and a sudden release of endorphins, leading to a feeling of pleasure. In males, orgasm usually occurs with release of semen.