The Collaborative International Dictionary of English v.0.48:

Debar \De*bar"\, v. t. [imp. & p. p. Debarred; p. pr. & vb. n.
   Debarring.] [Pref. de- + bar.]
   To cut off from entrance, as if by a bar or barrier; to
   preclude; to hinder from approach, entry, or enjoyment; to
   shut out or exclude; to deny or refuse; -- with from, and
   sometimes with of.
   [1913 Webster]

         Yet not so strictly hath our Lord imposed
         Labor, as to debar us when we need
         Refreshment.                             --Milton.
   [1913 Webster]

         Their wages were so low as to debar them, not only from
         the comforts but from the common decencies of civilized
         life.                                    --Buckle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

debar
    v 1: bar temporarily; from school, office, etc. [syn: suspend,
         debar]
    2: prevent the occurrence of; prevent from happening; "Let's
       avoid a confrontation"; "head off a confrontation"; "avert a
       strike" [syn: debar, forefend, forfend, obviate,
       deflect, avert, head off, stave off, fend off,
       avoid, ward off]
    3: prevent from entering; keep out; "He was barred from
       membership in the club" [syn: bar, debar, exclude]

Moby Thesaurus II by Grady Ward, 1.0:

93 Moby Thesaurus words for "debar":
   anticipate, avert, ban, bar, bar out, barricade, bate, block,
   block up, blockade, bolt, chock, choke, choke off, close,
   close off, close tight, close up, constrict, count out, crowd,
   cut off, deflect, deny, deter, disallow, discourage, dishearten,
   dog, eliminate, embargo, enjoin, estop, except, exclude,
   exclude from, fend, fend off, forbid, foreclose, forestall,
   freeze out, help, hinder, ignore, impede, inhibit, interdict, jam,
   keep from, keep off, keep out, leave out, lock, lock out, obstruct,
   obviate, occlude, omit, ostracize, outlaw, pack, pass over,
   preclude, prevent, prohibit, proscribe, refuse, reject, relegate,
   repel, repress, repudiate, rule out, save, say no to,
   send to Coventry, shut off, shut out, shut tight, squeeze,
   squeeze shut, stave off, stifle, stop up, strangle, strangulate,
   suffocate, suppress, suspend, taboo, turn aside, ward off