early 15c., "to punish by a fine or forfeiture," from Latin mulctare, altered (Barnhart calls it "false archaism") from multare "punish, to sentence to pay a fine," from multa "penalty, fine," which is perhaps from Oscan or Samnite [Klein], or perhaps connected to multus "numerous, many," as "a fine is a 'quantity' one has to pay" [de Vaan]. Sense of "defraud" is first recorded 1748. Related: Mulcted; mulcting; mulctation (early 15c.).