incorrigible

Etymology

From Middle English incorrigible, from Middle French incorrigible (1334), or directly from Latin incorrigibilis (“not to be corrected”), from in- (“not”) + corrigere (“to correct”) + -ibilis (“-able”). Recorded since 1340.

adj

1. Defective and impossible to materially correct or set aright.
   The construction flaw is incorrigible; any attempt to amend it would cause a complete collapse.
2. Incurably depraved; not reformable.
   His dark soul was too incorrigible to repent, even at his execution.
3. Impervious to correction by punishment or pain.
4. Unmanageable.
   Gordon Brown may have his grumpy, Granita moments, but as a strategist he is an incorrigible optimist. 7 December 2006, Michael White, “Breaking up is hard to do, even at the Treasury”, in The Guardian, London
5. Determined, unalterable, hence impossible to improve upon.
   The laws of nature and mathematics are incorrigible.
6. (archaic) Incurable.
   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

noun

1. An incorrigibly bad individual.
   The incorrigibles in the prison population are either lifers or habitual reoffenders.