The Collaborative International Dictionary of English v.0.48:

Unloose \Un*loose"\, v. t. [1st pref. un- (intensive) + loose.]
   To make loose; to loosen; to set free. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Unloose \Un*loose"\, v. i.
   To become unfastened; to lose all connection or union.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unloose
    v 1: grant freedom to; free from confinement [syn: free,
         liberate, release, unloose, unloosen, loose]
         [ant: confine, detain]
    2: loosen the ties of; "unloose your sneakers" [syn: unloose,
       unloosen]