The Collaborative International Dictionary of English v.0.48:

disabuse \dis`a*buse"\, v. t. [imp. & p. p. Disabused; p. pr.
   & vb. n. Disabusing.] [Pref. dis- + abuse; cf. F.
   d['e]sabuser.]
   To set free from mistakes; to undeceive; to disengage from
   fallacy or deception; to set right; -- often used with of;
   as, to disabuse one of his illusions.
   [1913 Webster]

         To undeceive and disabuse the people.    --South.
   [1913 Webster]

         If men are now sufficiently enlightened to disabuse
         themselves or artifice, hypocrisy, and superstition,
         they will consider this event as an era in their
         history.                                 --J. Adams.
   [1913 Webster]

WordNet (r) 3.0 (2006):

disabuse
    v 1: free somebody (from an erroneous belief)

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "disabuse":
   amend, awaken, break the spell, burst the bubble, conflict,
   contention, correct, debunk, difference, disaccord, disappoint,
   disenchant, disillude, disillusion, disillusionize, dissension,
   dissent, dissidence, disunity, emend, enlighten, expose, free,
   illuminate, let down easy, let in on, liberate, prick the bubble,
   purge, put straight, rectify, redress, release, set right,
   set straight, show up, strife, tell the truth, unblindfold,
   uncharm, undeceive, unspell, wake up



The Devil's Dictionary (1881-1906):

DISABUSE, v.t.  The present your neighbor with another and better
error than the one which he has deemed it advantageous to embrace.