The Collaborative International Dictionary of English v.0.48:

unconscious \un*con"scious\ ([u^]n*k[o^]n"sh[u^]s), a.
   1. Not conscious; having no consciousness or power of mental
      perception; without cerebral appreciation; hence, not
      knowing or regarding; ignorant; as, an unconscious man.
      --Cowper.
      [1913 Webster]

   2. Not known or apprehended by consciousness; resulting from
      neural activity of which a person is not aware; as, an
      unconscious movement; unconscious cerebration.
      "Unconscious causes." --Blackmore.
      [1913 Webster]

   3. Having no knowledge by experience; -- followed by of; as,
      a mule unconscious of the yoke. --Pope.
      [1913 Webster]

   4. Unintentional; as, an unconscious insult.
      [PJC] -- Un*con"scious*ly, adv. -- Un*con"scious*ness,
      n.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

unconscious \un*con"scious\ ([u^]n*k[o^]n"sh[u^]s), n.
   (Psychoanalysis)
   Usually

   the unconscious; that part of the mind in which mental
      processes occur that are not accesible to the awareness,
      but may significantly influence behavior.
      [PJC]
      [1913 Webster]

WordNet (r) 3.0 (2006):

unconscious
    adj 1: not conscious; lacking awareness and the capacity for
           sensory perception as if asleep or dead; "lay unconscious
           on the floor" [ant: conscious]
    2: without conscious volition
    3: (followed by `of') not knowing or perceiving; "happily
       unconscious of the new calamity at home"- Charles Dickens
    n 1: that part of the mind wherein psychic activity takes place
         of which the person is unaware [syn: unconscious mind,
         unconscious]

Moby Thesaurus II by Grady Ward, 1.0:

196 Moby Thesaurus words for "unconscious":
   a stranger to, abiotic, absent, absentminded, absorbed, abstracted,
   anima, asleep, automatic, azoic, bemused, blind, blind to,
   castle-building, casual, cataleptic, catatonic, caught napping,
   coconscious, cold, collective unconscious, comatose, compulsive,
   conditioned, conscience, conscious self, daydreaming, daydreamy,
   dead, dead asleep, dead to, deaf, deaf to, death instinct,
   deep asleep, doped, dormant, dreaming, dreamy, drowsing, drugged,
   dumb, ecstatic, ego, ego ideal, ego-id conflict, elsewhere,
   engrossed, ethical self, exanimate, faraway, fast asleep,
   flaked-out, forced, foreconscious, gut, half-awake, half-conscious,
   id, ill-advised, ill-considered, ill-devised, impercipient,
   impulsive, in a reverie, in ignorance of, in the clouds,
   inadvertent, inanimate, inanimated, incognizant, indeliberate,
   inert, inherent, innate, insensate, insensible, insensible to,
   insentient, instinctive, involuntary, knocked out, libidinal,
   libidinal energy, libido, lifeless, lost, lost in thought, lost to,
   mechanical, meditative, mind, mindless, mooning, moonraking,
   motive force, museful, musing, mute, napping, narcotized, natural,
   nirvanic, nodding, nonconceiving, nonconscious, nonliving,
   not with it, numb, oblivious, out, out cold, out of it, pensive,
   persona, personality, pipe-dreaming, pleasure principle,
   preconscious, preoccupied, primitive self, psyche,
   psychic apparatus, racial unconscious, rapt, reflex, reflexive,
   self, semiconscious, senseless, sleeping, slumbering, snap,
   somewhere else, soulless, sound asleep, spaced out, spontaneous,
   stargazing, stoned, strung out, stunned, subconscious,
   subconscious mind, subliminal, subliminal self, submerged mind,
   superego, taken up, transported, unadvised, unanimated, unaware,
   unaware of, uncalculated, unconscious mind, unconscious of,
   unconsidered, undeliberate, undeliberated, undesigned, unfeeling,
   unguarded, unguided, unhearing, unheeding, uninsightful,
   unintended, unintentional, unknowing, unlearned, unmeant,
   unmeditated, unmindful, unmindful of, unperceiving, unplanned,
   unprehensive, unpremeditated, unprompted, unpurposed, unrealizing,
   unseeing, unstudied, unsuspecting, unthinking, unthought-of,
   unwilled, unwilling, unwitting, vital impulse, witless,
   woolgathering, wrapped in thought, zonked, zonked out