The Collaborative International Dictionary of English v.0.48:

Foreclose \Fore*close"\, v. t. [imp. & p. p. Foreclosed; p.
   pr. & vb. n. Foreclosing.] [F. forclos, p. p. of forclore
   to exclude; OF. fors, F. hors, except, outside (fr. L. foris
   outside) + F. clore to close. See Foreign, and Close, v.
   t.]
   To shut up or out; to preclude; to stop; to prevent; to bar;
   to exclude.
   [1913 Webster]

         The embargo with Spain foreclosed this trade. --Carew.
   [1913 Webster]

   To foreclose a mortgager (Law), to cut him off by a
      judgment of court from the power of redeeming the
      mortgaged premises, termed his equity of redemption.

   To foreclose a mortgage, (not technically correct, but
      often used to signify) the obtaining a judgment for the
      payment of an overdue mortgage, and the exposure of the
      mortgaged property to sale to meet the mortgage debt.
      --Wharton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

foreclose
    v 1: keep from happening or arising; make impossible; "My sense
         of tact forbids an honest answer"; "Your role in the
         projects precludes your involvement in the competitive
         project" [syn: prevent, forestall, foreclose,
         preclude, forbid]
    2: subject to foreclosing procedures; take away the right of
       mortgagors to redeem their mortgage

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "foreclose":
   anticipate, avert, bar, cut off, debar, deflect, deter, discourage,
   disendow, dishearten, disherison, disinherit, disown, dispossess,
   disseise, estop, evict, exclude, expropriate, fend, fend off,
   forbid, forestall, help, keep from, keep off, obviate, preclude,
   prevent, prohibit, repel, rule out, save, stave off, turn aside,
   ward off