NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,790 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.

varicose vein
(VAYR-ih-kose vayn)
A condition in which a vein, most often in the legs, becomes permanently enlarged, twisted, and painful. This may be caused by valves in the vein that don’t work properly or by weakness in the vein walls.