Source : Webster's Revised Unabridged Dictionary (1913)

Incorrigible \In*cor"ri*gi*ble\, a. [L. incorrigibilis: cf. F.
   incorrigible. See {In-} not, and {Corrigible}.]
   Not corrigible; incapable of being corrected or amended; bad
   beyond correction; irreclaimable; as, incorrigible error.
   ``Incorrigible fools.'' --Dryden.

Incorrigible \In*cor"ri*gi*ble\, n.
   One who is corrigible; especially, a hardened criminal; as,
   the perpetual imprisonment of incorrigibles.

Source : WordNet®

incorrigible
     adj : impervious to correction by punishment [ant: {corrigible}]