The Collaborative International Dictionary of English v.0.48:

Deceptive \De*cep"tive\, a. [Cf. F. d['e]ceptif. See Deceive.]
   Tending to deceive; having power to mislead, or impress with
   false opinions; as, a deceptive countenance or appearance.
   [1913 Webster]

         Language altogether deceptive, and hiding the deeper
         reality from our eyes.                   --Trench.
   [1913 Webster]

   Deceptive cadence (Mus.), a cadence on the subdominant, or
      in some foreign key, postponing the final close.
      [1913 Webster]

WordNet (r) 3.0 (2006):

deceptive
    adj 1: causing one to believe what is not true or fail to
           believe what is true; "deceptive calm"; "a delusory
           pleasure" [syn: deceptive, delusory]
    2: designed to deceive or mislead either deliberately or
       inadvertently; "the deceptive calm in the eye of the storm";
       "deliberately deceptive packaging"; "a misleading
       similarity"; "statistics can be presented in ways that are
       misleading"; "shoddy business practices" [syn: deceptive,
       misleading, shoddy]

Moby Thesaurus II by Grady Ward, 1.0:

120 Moby Thesaurus words for "deceptive":
   Barmecidal, Barmecide, aberrant, abroad, adrift, airy, all abroad,
   all off, all wrong, amiss, apparent, apparently sound,
   apparitional, askew, astray, at fault, autistic, awry, beguiling,
   beside the mark, bogus, casuistic, catchy, chimeric, colorable,
   corrupt, counterfeit, deceitful, deceiving, defective, deluding,
   delusional, delusionary, delusive, delusory, dereistic, deviant,
   deviational, deviative, dishonest, disingenuous, distorted,
   dreamlike, dreamy, dubious, elusive, empty, errant, erring,
   erroneous, evasive, fake, fallacious, false, fantastic, faultful,
   faulty, fishy, flawed, fraudulent, hallucinatory, heretical,
   heterodox, hollow, illogical, illusional, illusionary, illusive,
   illusory, imaginary, insincere, jesuitic, misleading, not right,
   not true, off, off the track, ostensible, out, overrefined,
   oversubtle, peccant, perverse, perverted, phantasmagoric,
   phantasmal, phantom, philosophistic, plausible, pseudo,
   questionable, seeming, self-contradictory, self-deceptive,
   self-deluding, shifty, slippery, sophistic, sophistical, specious,
   spectral, spurious, straying, supposititious, trickish, tricksy,
   tricky, unactual, unfactual, unfounded, unorthodox, unproved,
   unreal, unreliable, unsubstantial, untrue, untruthful, visionary,
   wide, wrong