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mid-14c., "wicked," from Old French pervers "unnatural, degenerate; perverse, contrary" (12c.) and directly from Latin perversus "turned away, contrary, askew," figuratively, "turned away from what is right, wrong, malicious, spiteful," past participle of pervertere "to corrupt" (see pervert (v.)). The Latin word is glossed in Old English by forcerred, from past participle of forcyrran "to avoid," from cierran "to turn, return." Meaning "wrong, not in accord with what is accepted" is from 1560s; sense of "obstinate, stubborn" is from 1570s. It keeps the non-sexual senses of pervert (v.) and allows the psychological ones to go with perverted. Related: Perversely; perverseness.