The Collaborative International Dictionary of English v.0.48:

Dishearten \Dis*heart"en\ (d[i^]s*h[aum]rt"'n), v. t. [imp. & p.
   p. Disheartened (d[i^]s*h[aum]rt"'nd); p. pr. & vb. n.
   Disheartening.] [Pref. dis- + hearten.]
   To discourage; to deprive of courage and hope; to depress the
   spirits of; to deject.
   [1913 Webster]

         Regiments . . . utterly disorganized and disheartened.
                                                  --Macaulay.

   Syn: To dispirit; discourage; depress; deject; deter;
        terrify.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

disheartened \dis*heart"ened\ (d[i^]s*h[aum]rt"'nd), adj.
   made less hopeful or enthusiastic; as, their lack of interest
   disheartened the instructor. [Narrower terms: pessimistic
   (vs. optimistic)]

   Syn: demoralized, discouraged.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

disheartened
    adj 1: made less hopeful or enthusiastic; "desperate demoralized
           people looking for work"; "felt discouraged by the
           magnitude of the problem"; "the disheartened instructor
           tried vainly to arouse their interest" [syn:
           demoralized, demoralised, discouraged,
           disheartened]