beaver (n.) Look up beaver at Dictionary.com
Old English beofor, befer (earlier bebr), from Proto-Germanic *bebruz (source also of Old Saxon bibar, Old Norse bjorr, Middle Dutch and Dutch bever, Low German bever, Old High German bibar, German Biber), from PIE *bhebhrus, reduplication of root *bher- (3) "brown, bright" (source also of Lithuanian bebrus, Czech bobr, Welsh befer; see bear (n.) for the likely reason for this). Gynecological sense ("female genitals, especially with a display of pubic hair") is 1927 British slang, perhaps transferred from earlier meaning "a bearded man" (1910), or directly from the appearance of split beaver pelts.