'imperishably' originates from the Latin word 'imperitūrus,' where 'im-' meant 'not' and 'perīre' meant 'to perish.'

'imperitūrus' transformed into the Old French word 'imperissable,' and eventually became the modern English word 'imperishable,' with 'imperishably' as its adverbial form.

Initially, it meant 'not subject to decay or destruction,' and this meaning has largely remained the same in modern usage.