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]