unprovable

from WordNet (r) 3.0 (2006)

unprovable
    adj 1: not provable; "it was both unproved and unprovable"

from The Collaborative International Dictionary of English v.0.48

Unprovable \Unprovable\
   See {provable}.

from Moby Thesaurus II by Grady Ward, 1.0

39 Moby Thesaurus words for "unprovable":
      agnostic, ambiguous, capricious, chancy, changeable,
      controvertible, dicey, doubting, equivocal, erratic, fickle,
      hesitant, hesitating, incalculable, indecisive, indemonstrable,
      irresolute, polysemous, skeptical, touch-and-go, unaccountable,
      unattestable, uncertain, unconfirmable, unconvinced,
      undemonstrable, undemonstratable, undivinable, unforeseeable,
      unpersuaded, unpredictable, unsubstantiatable, unsupportable,
      unsure, unsustainable, unverifiable, variable, wavering,
      whimsical