The Collaborative International Dictionary of English v.0.48:

Oblivion \Ob*liv"i*on\, n. [L. oblivio, akin to oblivisci to
   forget: cf. OF. oblivion.]
   1. The act of forgetting, or the state of being forgotten;
      cessation of remembrance; forgetfulness.
      [1913 Webster]

            Second childishness and mere oblivion. --Shak.
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            Among our crimes oblivion may be set. --Dryden
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            The origin of our city will be buried in eternal
            oblivion.                             --W. Irving.
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   2. Official ignoring of offenses; amnesty, or general pardon;
      as, an act of oblivion. --Sir J. Davies.
      [1913 Webster]

   Syn: See Forgetfulness.
        [1913 Webster]

WordNet (r) 3.0 (2006):

oblivion
    n 1: the state of being disregarded or forgotten [syn:
         oblivion, limbo]
    2: total forgetfulness; "he sought the great oblivion of sleep"
       [syn: obliviousness, oblivion]

The Devil's Dictionary (1881-1906):

OBLIVION, n.  The state or condition in which the wicked cease from
struggling and the dreary are at rest.  Fame's eternal dumping ground.
Cold storage for high hopes.  A place where ambitious authors meet
their works without pride and their betters without envy.  A dormitory
without an alarm clock.