'irrevocability' originates from Latin, specifically from the Late Latin word 'irrevocabilis', where the prefix 'in-/ir-' meant 'not' (negative) and 'revocare' meant 'to call back'.

'irrevocabilis' in Late Latin passed into Old French and Middle English as 'irrevocable' (adjective), and the abstract noun 'irrevocability' developed later in English by adding the noun-forming suffix '-ity' to the adjective 'irrevocable'.

Initially it meant 'not able to be called back' in the literal sense; over time it evolved to the broader modern meaning of 'unable to be revoked, canceled, or changed' (final/permanent).