'irreversibility' originates from Latin via Late Latin and French, specifically from the Late Latin word 'reversibilis' with the prefix 'in-' (meaning 'not') and the noun-forming suffix '-ity' (from Latin '-itas').

'irreversibility' changed from the adjective 'irreversible' + the noun suffix '-ity'; 'reverse' itself comes from Old French 'reverser' and Latin 'revertere' ('re-' meaning 'back' and 'vertere' meaning 'to turn'), and these forms eventually produced the modern English word 'irreversibility'.

Initially it meant 'the state or quality of not being able to be turned back'; over time the core meaning has been retained while also being extended for technical use (for example, to describe entropy-related irreversibility in thermodynamics).