'reapportion' originates from the prefix 're-' meaning 'again' and the word 'apportion' from Latin 'apportionare', where 'ad-' meant 'to' and 'portionare' meant 'to divide'.

'apportionare' transformed into the Old French word 'apportioner', and eventually became the modern English word 'apportion', with 're-' added to form 'reapportion'.

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