The Collaborative International Dictionary of English v.0.48:

Dispirit \Dis*pir"it\, v. t. [imp. & p. p. Dispirited; p. pr.
   & vb. n. Dispiriting.] [Pref. dis- + spirit.]
   1. To deprive of cheerful spirits; to depress the spirits of;
      to dishearten; to discourage.
      [1913 Webster]

            Not dispirited with my afflictions.   --Dryden.
      [1913 Webster]

            He has dispirited himself by a debauch. --Collier.
      [1913 Webster]

   2. To distill or infuse the spirit of. [Obs. or R.]
      [1913 Webster]

            This makes a man master of his learning, and
            dispirits the book into the scholar.  --Fuller.

   Syn: To dishearten; discourage; deject; damp; depress; cast
        down; intimidate; daunt; cow.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

dispiriting \dispiriting\ adj.
   causing dejection; discouraging. Opposite of encouraging.

   Syn: demoralizing, demoralising, disheartening.
        [WordNet 1.5]

   2. causing dejection or depression.

   Syn: black, dark, depressing, grim.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

dispiriting
    adj 1: destructive of morale and self-reliance [syn:
           demoralizing, demoralising, disheartening,
           dispiriting]