incorrigible

1. not comparableDefective and impossible to materially correct or set aright.

   The construction flaw is incorrigible; any attempt to amend it would cause a complete collapse.

   Synonyms: irreparable, uncorrectable

2. not comparableUnmanageable; impervious to correction by punishment or pain.

   an incorrigible youth

3. not comparableIncurably depraved; not reformable.

   His dark soul was too incorrigible to repent, even at his execution.

   Synonyms: irredeemable, unreformable, reprobate

4. not comparableUnchangeably established in a belief or habit.

   Gordon Brown may have his grumpy, Granita moments, but as a strategist he is an incorrigible optimist.

   2006 December 7, Michael White, “Breaking up is hard to do, even at the Treasury”, in The Guardian, London

   Synonyms: determined, dyed-in-the-wool, hopeless, incurable, unalterable

5. not comparablehuman sciencesIntrinsically incapable of being corrected; impossible to disprove, by its very nature.

   The statement "My knee hurts" is incorrigible.

6. archaicnot comparableImpossible to cure.

   It may appear as an epidemic, as a hereditary complaint, or as an obstinate and incorrigible disease again and again recurring.

   1859, The British Journal of Psychiatry, volume 6, page 312

plural incorrigibles

1. An incorrigibly bad person.

   The incorrigibles in the prison population are either lifers or habitual reoffenders.