'irreducible' originates from Latin, specifically the word 'irreducibilis,' where 'in-' meant 'not' and 'reducere' meant 'to bring back or reduce.'

'irreducibilis' transformed into the French word 'irréductible,' and eventually became the modern English word 'irreducible' through Middle English.

Initially, it meant 'not able to be brought back or reduced,' and this meaning has largely remained the same in modern usage.