The Collaborative International Dictionary of English v.0.48:

Encourage \En*cour"age\ (?; 48), v. t. [imp. & p. p.
   Encouraged (?; 48); p. pr. & vb. n. Encouraging.] [F.
   encourager; pref. en- (L. in) + courage courage. See
   Courage.]
   To give courage to; to inspire with courage, spirit, or hope;
   to raise, or to increase, the confidence of; to animate;
   enhearten; to incite; to help forward; -- the opposite of
   discourage.
   [1913 Webster]

         David encouraged himself in the Lord.    --1 Sam. xxx.
                                                  6.

   Syn: To embolden; inspirit; animate; enhearten; hearten;
        incite; cheer; urge; impel; stimulate; instigate;
        countenance; comfort; promote; advance; forward;
        strengthen.
        [1913 Webster]

WordNet (r) 3.0 (2006):

encourage
    v 1: contribute to the progress or growth of; "I am promoting
         the use of computers in the classroom" [syn: promote,
         advance, boost, further, encourage]
    2: inspire with confidence; give hope or courage to [ant:
       discourage]
    3: spur on; "His financial success encouraged him to look for a
       wife"

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "encourage":
   abet, admonish, advance, advantage, advocate, aid, aid and abet,
   animate, ask for, assist, assure, bear up, bolster, boost,
   brace up, brighten, buck up, buoy up, caution, charge, cheer,
   cheer up, chirk up, comfort, condole with, conduce to, console,
   contribute to, countenance, ease, egg on, embolden, endorse,
   enjoin, enliven, exhilarate, exhort, expedite, expostulate,
   facilitate, favor, feed, forward, foster, further, give a lift,
   give comfort, give encouragement, gladden, go for, hasten, hearten,
   help, incite, induce, inspire, inspirit, invigorate, invite,
   issue a caveat, keep in countenance, lend wings to, liven,
   make for, move, nerve, nourish, nurture, pep up, persuade, pick up,
   preach, promote, prompt, push forward, put at ease, put forward,
   quicken, reassure, rejoice, rejoice the heart, relieve,
   remonstrate, set at ease, set forward, shine upon, smile upon,
   solace, speed, stimulate, subscribe, subsidize, support,
   sympathize with, urge, vitalize, warn