'apanage' originates from French, specifically the word 'apanage', ultimately from Medieval Latin 'apanagium' (or 'apanaticum'), where the element is related to Latin 'ad' (to) + 'panis' (bread, provision) suggesting a provision or allowance.

'apanagium' in Medieval Latin passed into Old French as 'apanage' and was borrowed into English with the sense of a provision or grant; over time the form and spelling stabilized as 'apanage'.

Initially it referred to a provision or allowance (literally related to 'bread' or sustenance) and later came to mean a grant of land/income or a distinctive privilege attached to rank or office.