The Collaborative International Dictionary of English v.0.48:

Unwary \Un*wa"ry\, a. [Cf. Unware.]
   [1913 Webster]
   1. Not vigilant against danger; not wary or cautious;
      unguarded; precipitate; heedless; careless.
      [1913 Webster]

   2. Unexpected; unforeseen; unware. [Obs.] --Spenser.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unwary
    adj 1: not alert to danger or deception; "the shrieks of unwary
           animals taken by surprise"; "some thieves prey especially
           on unwary travelers"; "seduce the unwary reader into easy
           acquiescence"- O.J.Campbell [ant: wary]

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "unwary":
   artless, asleep, bluff, blunt, born yesterday, brash, brazen,
   brazenfaced, candid, careless, childlike, confiding,
   culpably negligent, derelict, direct, foolhardy, frank,
   goofing off, guileless, hasty, heedless, hotheaded, hubristic,
   ill-advised, improvident, imprudent, impudent, inadvertent,
   inattentive, incautious, inconsiderate, indiscreet, ingenu,
   ingenuous, injudicious, innocent, insolent, laissez-faire, lax,
   loose, mindless, naive, napping, neglectful, neglecting, negligent,
   nodding, noninterfering, nonrestrictive, off-guard, open,
   openhearted, outspoken, overbold, overcareless, overconfident,
   overly permissive, oversure, overweening, permissive, plain,
   procrastinating, rash, reckless, relaxed, remiss, scamping, simple,
   simplehearted, simpleminded, sincere, single-hearted,
   single-minded, skimping, slack, sleeping, slighting, slurring,
   temerarious, thoughtless, trustful, trusting, unadvised, unalert,
   uncautious, unchary, uncircumspect, unguarded, unprepared, unready,
   unreserved, unrigorous, unsophisticated, unthinking, unvigilant,
   unwatchful, unwise