'indigestible' originates from Latin, specifically the word 'indigestibilis,' where 'in-' meant 'not' and 'digestibilis' meant 'able to be digested.'

'indigestibilis' transformed into the Old French word 'indigestible,' and eventually became the modern English word 'indigestible' through Middle English.

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