'irrefutably' originates from the Latin word 'irrefutabilis', where 'in-' meant 'not' and 'refutabilis' meant 'able to be refuted'.

'irrefutabilis' transformed into the French word 'irréfutable', and eventually became the modern English word 'irrefutable' through Middle English.

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