The Collaborative International Dictionary of English v.0.48:

Dishevel \Di*shev"el\, v. i.
   To be spread in disorder or hang negligently, as the hair.
   [R.] --Sir T. Herbert.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dishevel \Di*shev"el\ (d[i^]*sh[e^]v"'l or -[e^]l), v. t. [imp.
   & p. p. Disheveledor Dishevelled; p. pr. & vb. n.
   Disheveling or Dishevelling.] [OF. descheveler, F.
   d['e]cheveler, LL. discapillare; dis- + L. capillus the hair
   of the head. See Capillary.]
   1. To suffer (the hair) to hang loosely or disorderly; to
      spread or throw (the hair) in disorder; -- used chiefly in
      the passive participle.
      [1913 Webster]

            With garments rent and hair disheveled,
            Wringing her hands and making piteous moan.
                                                  --Spenser.
      [1913 Webster]

   2. To spread loosely or disorderly.
      [1913 Webster]

            Like the fair flower disheveled in the wind.
                                                  --Cowper.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dishevel
    v 1: disarrange or rumple; dishevel; "The strong wind tousled my
         hair" [syn: tousle, dishevel, tangle]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "dishevel":
   clutter, confuse, derange, disarrange, disarray, discompose,
   dislocate, disorder, disorganize, disturb, jumble,
   knock galley-west, litter, mess, mess up, misarrange, muddle, muss,
   muss up, perturb, ruffle, rumple, scatter, tousle, unsettle,
   upset