The Collaborative International Dictionary of English v.0.48:

Consciousness \Con"scious*ness\, n.
   1. The state of being conscious; knowledge of one's own
      existence, condition, sensations, mental operations, acts,
      etc.
      [1913 Webster]

            Consciousness is thus, on the one hand, the
            recognition by the mind or "ego" of its acts and
            affections; -- in other words, the self-affirmation
            that certain modifications are known by me, and that
            these modifications are mine.         --Sir W.
                                                  Hamilton.
      [1913 Webster]

   2. Immediate knowledge or perception of the presence of any
      object, state, or sensation. See the Note under
      Attention.
      [1913 Webster]

            Annihilate the consciousness of the object, you
            annihilate the consciousness of the operation. --Sir
                                                  W. Hamilton.
      [1913 Webster]

            And, when the steam
            Which overflowed the soul had passed away,
            A consciousness remained that it had left.
            . . . images and precious thoughts
            That shall not die, and can not be destroyed.
                                                  --Wordsworth.
      [1913 Webster]

            The consciousness of wrong brought with it the
            consciousness of weakness.            --Froude.
      [1913 Webster]

   3. Feeling, persuasion, or expectation; esp., inward sense of
      guilt or innocence. [R.]
      [1913 Webster]

            An honest mind is not in the power of a dishonest:
            to break its peace there must be some guilt or
            consciousness.                        --Pope.
      [1913 Webster]

WordNet (r) 3.0 (2006):

consciousness
    n 1: an alert cognitive state in which you are aware of yourself
         and your situation; "he lost consciousness" [ant:
         unconsciousness]
    2: having knowledge of; "he had no awareness of his mistakes";
       "his sudden consciousness of the problem he faced"; "their
       intelligence and general knowingness was impressive" [syn:
       awareness, consciousness, cognizance, cognisance,
       knowingness] [ant: incognizance]