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]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "liberate":
   affranchise, appropriate, cast off, clear, deliver, detach,
   disburden, discharge, disembarrass, disembroil, disencumber,
   disengage, disentangle, disenthrall, disinvolve, doff, ease,
   emancipate, enfranchise, extract, extricate, free, free up, let go,
   let loose, let off, let out, loose, loosen, manumit, pilfer,
   purloin, ransom, recover, redeem, release, remove, rescue,
   retrieve, salvage, save, set at large, set at liberty, set free,
   steal, take, take off, unbar, unbind, unbolt, unbuckle, unbutton,
   unchain, unclasp, unclutter, undo, unfasten, unfetter, unglue,
   unlace, unlatch, unleash, unlock, unloose, unloosen, unscramble,
   unshackle, unsnarl, unstick, unstrap, untangle, untie,
   weigh anchor



Bouvier's Law Dictionary, Revised 6th Ed (1856):

LIBERATE, English practice. A writ which issues on lands, tenements, and
chattels, being returned under an extent on a statute staple, commanding the
sheriff to deliver them to the plaintiff, by the extent and appraisement
mentioned in the writ of extent, and in the sheriff's return thereto. See
Com dig. Statute Staple, D 6.