'apportionable' originates from the Latin word 'apportionare,' where 'ad-' meant 'to' and 'portionare' meant 'to divide into portions.'

'apportionare' transformed into the Old French word 'apportioner,' and eventually became the modern English word 'apportion' through Middle English.

Initially, it meant 'to divide into portions,' and this meaning has largely remained the same in modern usage.