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]

The Collaborative International Dictionary of English v.0.48:

disheveled \di*shev"eled\, dishevelled \di*shev"elled\, a.
   1. Hanging in loose disorder; disarranged; in disarray; not
      made neat; -- used especially of hair or clothing; as,
      disheveled hair.
      [1913 Webster]

   2. Having the hair in loose disorder.
      [1913 Webster]

            The dancing maidens are disheveled M[ae]nads. --J.
                                                  A. Symonds.
      [1913 Webster]

WordNet (r) 3.0 (2006):

disheveled
    adj 1: in disarray; extremely disorderly; "her clothing was
           disheveled"; "powder-smeared and frowzled"; "a rumpled
           unmade bed"; "a bed with tousled sheets"; "his brown hair
           was tousled, thick, and curly"- Al Spiers [syn:
           disheveled, dishevelled, frowzled, rumpled,
           tousled]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "disheveled":
   matted, messed up, messy, mussed up, raunchy, ruffled, rumpled,
   shaggy, slipshod, sloppy, snaggy, snarled, tousled, tously,
   tumbled, uncombed, unfastidious, unkempt, untidy