vagina (n.)
"sexual passage of the female from the vulva to the uterus," 1680s, medical Latin, from specialized use of Latin vagina "sheath, scabbard, covering; sheath of an ear of grain, hull, husk" (plural vaginae), from PIE *wag-ina- (cognates: Lithuanian vožiu "ro cover with a hollow thing"), from root *wag- "to break, split, bite." Probably the ancient notion is of a sheath made from a split piece of wood (see sheath). A modern medical word; the Latin word was not used in an anatomical sense in classical times. Anthropological vagina dentata is attested from 1902.