The Collaborative International Dictionary of English v.0.48:

Disorient \Dis*o"ri*ent\, v. t.
   1. To turn away from the east; to confuse as to which way is
      east; to cause to lose one's bearings. [R.] --Bp.
      Warburton.
      [1913 Webster]

   2. to cause (a person) to lose one's sense of direction; to
      cause to lose one's bearings or way; as, the tourist was
      disoriented by the winding and narrow streets.
      [PJC]

   3. (Psychiatry) to cause one to lose one's sense of time or
      place, or of one's own personal identity.
      [PJC]

   4. to confuse (a person) by changing or removing something
      which has served as a standard or guide to action; as,
      workers were rendered unemployed and disoriented by the
      rapid changes in the markets.
      [PJC]

WordNet (r) 3.0 (2006):

disorient
    v 1: cause to be lost or disoriented [syn: disorient,
         disorientate] [ant: orient, orientate]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "disorient":
   addle, addle the wits, ball up, becloud, bedazzle, befuddle,
   bewilder, bother, bug, cloud, confuse, daze, dazzle,
   discombobulate, discomfit, discompose, disconcert, disorganize,
   disturb, embarrass, entangle, flummox, flurry, fluster, flutter,
   fog, fuddle, fuss, maze, mist, mix up, moider, muddle, perplex,
   perturb, pother, put out, raise hell, rattle, ruffle,
   throw into confusion, unsettle, upset