The Collaborative International Dictionary of English v.0.48:

Enliven \En*liv"en\, v. t. [imp. & p. p. Enlivened; p. pr. &
   vb. n. Enlivening.] [Pref. en- + liven.].
   1. To give life, action, or motion to; to make vigorous or
      active; to excite; to quicken; as, fresh fuel enlivens a
      fire.
      [1913 Webster]

            Lo! of themselves th' enlivened chessmen move.
                                                  --Cowley.
      [1913 Webster]

   2. To give spirit or vivacity to; to make sprightly, gay, or
      cheerful; to animate; as, mirth and good humor enliven a
      company; enlivening strains of music.

   Syn: To animate; rouse; inspire; cheer; encourage; comfort;
        exhilarate; inspirit; invigorate.
        [1913 Webster]

WordNet (r) 3.0 (2006):

enliven
    v 1: heighten or intensify; "These paintings exalt the
         imagination" [syn: inspire, animate, invigorate,
         enliven, exalt]
    2: make lively; "let's liven up this room a bit" [syn:
       enliven, liven, liven up, invigorate, animate]
       [ant: blunt, deaden]

Moby Thesaurus II by Grady Ward, 1.0:

99 Moby Thesaurus words for "enliven":
   amuse, animate, arouse, awaken, beguile, boost, brace, brace up,
   brighten, brisk, brisken, buck up, buoy up, cheer, cheer up,
   chirk up, convulse, delight, divert, dynamize, electrify, embue,
   encourage, energize, enkindle, entertain, excite, exhilarate,
   fillip, fire, fire up, fortify, fracture one, fresh up, freshen,
   freshen up, galvanize, give a lift, gladden, hearten, imbue,
   infect, inflame, inform, infuse, infuse life into, inject,
   inoculate, inspire, inspirit, invigorate, jazz up, kill, kindle,
   knock dead, liven, loosen up, pep up, perk up, pick up, pique,
   provoke, quicken, raise a laugh, raise a smile, reanimate,
   recreate, refresh, refreshen, regale, reinvigorate, rejoice,
   rejoice the heart, rejuvenate, relax, renew, restore, resuscitate,
   revive, revivify, rouse, set up, sharpen, slay, snap up, solace,
   spirit, spirit up, stimulate, tickle, titillate, uplift, vitalize,
   vivify, wake up, warm, whet, wow, zip up