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by 1902 (earlier procto-colonoscopy, 1896; colonoscope attested from 1884), from colon (n.2) + -oscopy (see -scope).
colonoscopy co·lon·os·co·py (kō'lə-nŏs'kə-pē)n. Examination of the inner surface of the colon by means of a colonoscope. Also called coloscopy.