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]

WordNet (r) 3.0 (2006):

dispirit
    v 1: lower someone's spirits; make downhearted; "These news
         depressed her"; "The bad state of her child's health
         demoralizes her" [syn: depress, deject, cast down,
         get down, dismay, dispirit, demoralize,
         demoralise] [ant: elate, intoxicate, lift up, pick
         up, uplift]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "dispirit":
   beat down, cast down, chill, damp, dampen, dampen the spirits,
   darken, dash, deject, demoralize, depress, discourage, dishearten,
   disparage, knock down, lower, lower the spirits, oppress,
   press down, sadden, sink, weigh heavy upon, weigh upon