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]