The Collaborative International Dictionary of English v.0.48:

Liberate \Lib"er*ate\ (-[=a]t), v. t. [imp. & p. p. Liberated
   (-[=a]`t[e^]d); p. pr. & vb. n. Liberating
   (-[=a]`t[i^]ng).] [L. liberatus, p. p. of liberare to free,
   fr. liber free. See Liberal, a., and cf. Deliver.]
   To release from restraint or bondage; to set at liberty; to
   free; to manumit; to disengage; as, to liberate a slave or
   prisoner; to liberate the mind from prejudice; to liberate
   gases.
   [1913 Webster]

   Syn: To deliver; free; release. See Deliver.
        [1913 Webster]

WordNet (r) 3.0 (2006):

liberate
    v 1: give equal rights to; of women and minorities [syn:
         emancipate, liberate]
    2: grant freedom to; free from confinement [syn: free,
       liberate, release, unloose, unloosen, loose] [ant:
       confine, detain]
    3: grant freedom to; "The students liberated their slaves upon
       graduating from the university" [syn: liberate, set free]
    4: release (gas or energy) as a result of a chemical reaction or
       physical decomposition [syn: release, free, liberate]