The Collaborative International Dictionary of English v.0.48:

Disenfranchise \Dis`en*fran"chise\, v. t.
   To disfranchise; to deprive of the rights of a citizen. --
   Dis`en*fran"chise*ment, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

disenfranchise
    v 1: deprive of voting rights [syn: disenfranchise,
         disfranchise] [ant: enfranchise]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "disenfranchise":
   deprive of freedom, disfranchise, dominate, enslave, enthrall,
   hold captive, hold down, hold in bondage, hold in captivity,
   hold in leash, hold in subjection, keep down, keep under,
   lead captive, make dependent, peonize, subject, subjugate,
   subordinate, take captive, vassalize