'aubaine' originates from French, specifically the Old French word 'alobaine' (later spelled 'aubaine'), where the element 'alo-' likely referred to 'other/foreign' and the element '-baine' was associated with an advantage or benefit.

'aubaine' changed from the Old French word 'alobaine' and later became the modern French 'aubaine', which was borrowed into English with its sense of an unexpected advantage.

Initially, it meant 'the right of a seigneur to claim the goods of a foreigner who died in his domain', but over time it evolved into its current meaning of 'an unexpected advantage or windfall'.