The Collaborative International Dictionary of English v.0.48:

Unwitting \Un*wit"ting\, a.
   Not knowing; unconscious; ignorant. -- Un*wit"ting*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unwitting
    adj 1: not done with purpose or intent; "an unintended slight";
           "an unintentional pun"; "the offense was unintentional";
           "an unwitting mistake may be overlooked" [syn:
           unintentional, unplanned, unwitting]
    2: not aware or knowing; "an unwitting subject in an experiment"
       [ant: witting]
    3: unaware because of a lack of relevant information or
       knowledge; "he was completely ignorant of the circumstances";
       "an unknowledgeable assistant"; "his rudeness was unwitting"
       [syn: ignorant, unknowledgeable, unknowing,
       unwitting]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "unwitting":
   a stranger to, asleep, automatic, blind, blind to, caught napping,
   compulsive, conditioned, dead to, deaf to, forced, impercipient,
   impulsive, in ignorance of, incognizant, insensible, insensible to,
   instinctive, involuntary, mechanical, mindless, napping,
   nonconceiving, not with it, oblivious, out of it, reflex,
   reflexive, unacquainted, unaware, unaware of, unconscious,
   unconscious of, undesigned, unfamiliar, unguarded, unguided,
   unhearing, uninformed, uninsightful, uninstructed, unintended,
   unintentional, unknowing, unmeant, unmeditated, unmindful,
   unmindful of, unperceiving, unplanned, unprehensive,
   unpremeditated, unprompted, unpurposed, unrealizing, unseeing,
   unsuspecting, unthinking, unthought-of, unwilled, unwilling,
   witless