The Collaborative International Dictionary of English v.0.48:

Mulct \Mulct\, n. [L. mulcta, multa.]
   1. A fine or penalty, esp. a pecuniary punishment or penalty.
      [1913 Webster]

   2. A blemish or defect. [Obs.]
      [1913 Webster]

   Syn: Amercement; forfeit; forfeiture; penalty.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mulct \Mulct\, v. t. [imp. & p. p. Mulcted; p. pr. & vb. n.
   Mulcting.] [L. mulctare, multare.]
   1. To punish for an offense or misdemeanor by imposing a fine
      or forfeiture, esp. a pecuniary fine; to fine.
      [1913 Webster]

   2. Hence, to deprive of; to withhold by way of punishment or
      discipline. [Obs.]
      [1913 Webster] Mulctary

WordNet (r) 3.0 (2006):

mulct
    n 1: money extracted as a penalty [syn: fine, mulct,
         amercement]
    v 1: deprive of by deceit; "He swindled me out of my
         inheritance"; "She defrauded the customers who trusted
         her"; "the cashier gypped me when he gave me too little
         change" [syn: victimize, swindle, rook, goldbrick,
         nobble, diddle, bunco, defraud, scam, mulct,
         gyp, gip, hornswoggle, short-change, con]
    2: impose a fine on; "he was fined for littering"