'insusceptible' originates from Latin, specifically the word 'insusceptibilis,' where 'in-' meant 'not' and 'susceptibilis' meant 'capable of being influenced.'

'insusceptibilis' transformed into the French word 'insusceptible,' and eventually became the modern English word 'insusceptible' through Middle English.

Initially, it meant 'not capable of being influenced,' and this meaning has largely remained the same in modern usage.