c. 1300 (transitive), "to turn someone aside from a right religious belief to a false or erroneous one," from Old French pervertir "pervert, undo, destroy" (12c.) and directly from Latin pervertere "overthrow, overturn," figuratively "to corrupt, subvert, abuse," literally "turn the wrong way, turn about," from per "away" (see per) + vertere "to turn, turn back, be turned; convert, transform, translate; be changed" (from PIE root *wer- (2) "to turn, bend").
Related: Perverted; perverting. Replaced native froward, which embodies the same image. Old English had mishweorfed "perverted, inverted," an identical formation to the Latin word using native elements.