Old English bugan "to bend, to bow down, to bend the body in condescension," also "to turn back" (class II strong verb; past tense beag, past participle bogen), from Proto-Germanic *bugon (cf. Dutch buigen, Middle Low German bugen, Old High German biogan, German biegen, Gothic biugan "to bend," Old Norse boginn "bent"), from *beugen, from PIE root *bheug- (3) "to bend," with derivatives referring to bent, pliable, or curved objects (cf. Sanskrit bhujati "bends, thrusts aside;" Old High German boug, Old English beag "a ring"). The noun in this sense is first recorded 1650s. Related: Bowed; bowing. Bow out "withdraw" is from 1942.