perversity n.

late 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." The meaning "wrong, not in accord with what is accepted or standard, turned away from what is right" is from 1560s; the sense of "obstinate in the wrong, 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.

Perverse has reference to one's attitude, in both conduct and opinion. The perverse person is settled in habit and disposition of contrariness; he not only likes or dislikes, acts or refuses to act, by the rule of contradiction to the wishes, commands, or opinions of others, especially of those whom he ought to consider, but be is likely even to take pains to do or say that which he knows to be offensive or painful to them. Perversity may be found in a child, but it is so settled an element of character as to be rather the mark of an adult. [Century Dictionary]