1615, coined in Mod.L., from Gk. kleitoris, a diminutive, but the exact sense is uncertain. Probably from Gk. kleiein "to sheathe," also "to shut," in reference to its being covered by the labia minora. The related noun form kleis has a second meaning of "a key, a latch or hook (to close a door)." Wooden pegs were the original keys; a connection also revealed in L. clovis "nail" and claudere "to shut" (see close (v.)). Some medical sources give a supposed Gk. verb kleitoriazein "to touch or titillate lasciviously, to tickle," lit. "to be inclined (toward pleasure)" (cf. Ger. slang der Kitzler "clitoris," lit. "the tickler"), related to Gk. kleitys, a variant of klitys "side of a hill," related to klinein "to slope," from the same root as climax. But many sources take kleitoris literally as Gk. "little hill." The It. anatomist Mateo Renaldo Colombo (1516-1559), professor at Padua, claimed to have discovered it (De re anatomica, 1559, p. 243). He called it amor Veneris, vel dulcedo "the love or sweetness of Venus." It had been known to women since much earlier, of course.