'aver' originates from Old French, specifically the word 'averer', ultimately from Late Latin '*adverare' or 'adverare', where 'ad-' meant 'to, toward' and it is related to 'verus' meaning 'true'.

'aver' changed from the Old French word 'averer' and Middle English 'averen' and eventually became the modern English verb 'aver'.

Initially, it meant 'to make true or prove to be true' (in legal contexts to confirm), but over time it evolved into the current meaning of 'to state or assert (something) to be true'.