'apportioner' originates from Old French, specifically the word 'apportioner', where the prefix 'a-' (from Latin 'ad-') meant 'to, toward' and 'portion' (from Latin 'portio') meant 'a part, share'.

'apportioner' changed from Old French 'apportioner' and Middle English forms such as 'apportiounen' and eventually became the modern English word 'apportioner'.

Initially, it meant 'one who divides or assigns parts or shares', and this basic meaning has largely remained the same in modern usage.