'impermissibly' originates from the Latin word 'permissibilis,' where 'per-' meant 'through' and 'mittere' meant 'to send.'

'permissibilis' transformed into the Old French word 'permissible,' and eventually became the modern English word 'impermissible' with the prefix 'im-' indicating negation.

Initially, it meant 'not allowed,' and this meaning has largely remained the same in modern usage.