Old English wrencan "to twist," from Proto-Germanic *wrankijanan (cf. Old High German renken, German renken "to twist, wrench," Old English wringan "to wring"), from PIE *wreng- "to turn" (cf. Sanskrit vrnakti "turns, twists," Lithuanian rengtis "to grow crooked, to writhe"), nasalized variant of *werg- "to turn" (cf. Latin vergere "to turn, tend toward"), from root *wer- (3) "to turn, bend" (see versus). Related: Wrenched, wrenching.
Old English wrenc "a twisting, artifice, trick;" see wrench (v.). The meaning "tool with jaws for turning" is first recorded 1794.