The Collaborative International Dictionary of English v.0.48:

Disillusion \Dis`il*lu"sion\, v. t.
   To free from an illusion; to disillusionize.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disillusion \Dis`il*lu"sion\, n.
   The act or process of freeing from an illusion, or the state
   of being freed therefrom. --Lowell.
   [1913 Webster]

WordNet (r) 3.0 (2006):

disillusion
    n 1: freeing from false belief or illusions [syn:
         disenchantment, disillusion, disillusionment]
    v 1: free from enchantment [syn: disenchant, disillusion]
         [ant: delight, enchant, enrapture, enthral,
         enthrall, ravish, transport]

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "disillusion":
   awaken, awakening, baffle, balk, ban, bilk, blackball,
   blackballing, break the spell, burst the bubble, cast down,
   complaint, correct, cross, dash, debunk, debunking, defeat,
   defeat expectation, dim view, disabuse, disagreement, disappoint,
   disappointment, disapprobation, disapproval, discontent,
   discontentedness, discontentment, disenchant, disenchantment,
   disesteem, disfavor, disgruntlement, disillude, disillusionize,
   disillusionment, displeasure, disrespect, dissatisfaction,
   dissatisfy, dissent, distaste, enlighten, enlightenment, exclusion,
   expose, foil, frustrate, indignation, let down, let down easy,
   let in on, low estimation, low opinion, objection, opposition,
   opposure, ostracism, prick the bubble, protest, put straight,
   rejection, return to reality, rude awakening, set right,
   set straight, show up, tantalize, tease, tell the truth,
   thumbs-down, thwart, unblindfold, uncharm, undeceive, undeception,
   unhappiness, unspell, unspelling, wake up