The Collaborative International Dictionary of English v.0.48:

Unresolvable \Unresolvable\
   See resolvable.

WordNet (r) 3.0 (2006):

unresolvable
    adj 1: not easily solved; "an apparantly insolvable problem";
           "public finance...had long presented problems unsolvable
           or at least unsolved"- C.L.Jones [syn: insolvable,
           unsoluble, unsolvable, unresolvable]
    2: not capable of being resolved; "unresolvable confusion"