The Collaborative International Dictionary of English v.0.48:

Unlace \Un*lace"\, v. t. [1st un- + lace.]
   [1913 Webster]
   1. To loose by undoing a lacing; as, to unlace a shoe.
      [1913 Webster]

   2. To loose the dress of; to undress; hence, to expose; to
      disgrace.
      [1913 Webster]

            What's the matter,
            That you unlace your reputation thus? --Shak.
      [1913 Webster]

   3. (Naut.) To loose, and take off, as a bonnet from a sail,
      or to cast off, as any lacing in any part of the rigging
      of a vessel. --Totten.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unlace
    v 1: undo the ties of; "They untied the prisoner" [syn: untie,
         unbrace, unlace] [ant: bind, tie]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "unlace":
   cast off, detach, disengage, doff, free, liberate, loose, loosen,
   release, remove, take off, unbar, unbind, unbolt, unbuckle,
   unbutton, unchain, unclasp, undo, unfasten, unfetter, unglue,
   unlatch, unleash, unlock, unloose, unloosen, unstick, unstrap,
   untie, weigh anchor