The Collaborative International Dictionary of English v.0.48:

Illusive \Il*lu"sive\, a. [See Illude.]
   Deceiving by false show; deceitful; deceptive; false;
   illusory; unreal.
   [1913 Webster]

         Truth from illusive falsehood to command. --Thomson.
   [1913 Webster]

WordNet (r) 3.0 (2006):

illusive
    adj 1: based on or having the nature of an illusion; "illusive
           hopes of finding a better job"; "Secret activities offer
           presidents the alluring but often illusory promise that
           they can achieve foreign policy goals without the
           bothersome debate and open decision that are staples of
           democracy" [syn: illusive, illusory]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "illusive":
   Barmecidal, Barmecide, Circean, airy, apparent, apparently sound,
   apparitional, autistic, beguiling, bewitching, casuistic, catchy,
   charming, chimeric, colorable, deceiving, deceptive, delusional,
   delusionary, delusive, delusory, dereistic, disingenuous,
   dreamlike, dreamy, dubious, empty, enchanting, entrancing,
   erroneous, fallacious, false, fantastic, fascinating, fishy,
   glamorous, hallucinatory, hollow, illusional, illusionary,
   illusory, imaginary, insincere, jesuitic, misleading, ostensible,
   overrefined, oversubtle, phantasmagoric, phantasmal, phantom,
   philosophistic, plausible, questionable, seeming, self-deceptive,
   self-deluding, sophistic, sophistical, specious, spectral,
   spellbinding, supposititious, trickish, tricksy, tricky, unactual,
   unfounded, unreal, unsubstantial, visionary, witching