The Collaborative International Dictionary of English v.0.48:

Obliteration \Ob*lit`er*a"tion\, n. [L. obliteratio: cf. F.
   oblit['e]ration.]
   The act of obliterating, or the state of being obliterated;
   extinction. --Sir. M. Hale.
   [1913 Webster]

WordNet (r) 3.0 (2006):

obliteration
    n 1: destruction by annihilating something [syn: annihilation,
         obliteration]
    2: the complete destruction of every trace of something [syn:
       eradication, obliteration]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "obliteration":
   Lethe, absentmindedness, blot, blotting, blotting out, cancel,
   cancellation, decay of memory, deletion, effacement, erasure,
   expunction, forgetfulness, forgetting, forgiveness, grace period,
   hazy recollection, heedlessness, moratorium, nepenthe, nirvana,
   oblivion, obliviousness, scrubbing, short memory, unmindfulness,
   washing out, waters of oblivion, wiping out, write-off