usurern.

usurer (n.)late 13c., "one who lends money at interest," but later especially "one who lends money at an exorbitant rate of interest," from Anglo-French usurer, Old French usurier, usureor, from Medieval Latin usurarius "money-lender, usurer," from Latin usurarius (adj.) "pertaining to interest; that pays interest," from usura (see usury).