c.1300, noun use of adv. phrase par amour (c.1300) "passionately, with strong love or desire," from Anglo-Fr. par amour, from acc. of amor "love," from amare "to love" (see Amy). Originally a term for Christ (by women) or the Virgin Mary (by men), it came to mean "darling, sweetheart"
(c.1350) and "mistress, concubine, clandestine lover" (late 14c.).