NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,855 terms related to cancer and medicine.

Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.

iris
(I-ris)
The colored tissue at the front of the eye that contains the pupil in the center. The iris helps control the size of the pupil to let more or less light into the eye.