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]