The Collaborative International Dictionary of English v.0.48:

Unrecognizable \Unrecognizable\
   See recognizable.

WordNet (r) 3.0 (2006):

unrecognizable
    adj 1: defying recognition as e.g. because of damage or
           alteration [syn: unrecognizable, unrecognisable]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "unrecognizable":
   blear, bleared, bleary, blurred, blurry, confused, dark, dim,
   faint, feeble, filmy, foggy, fuzzy, half-seen, half-visible, hazy,
   ill-defined, inconspicuous, indefinite, indistinct,
   indistinguishable, low-profile, merely glimpsed, misty, obscure,
   out of focus, pale, semivisible, shadowy, uncertain, unclear,
   undefined, unplain, vague, weak