'assai' originates from Italian, specifically the word 'assai', where 'ad' meant 'to' and 'satis' meant 'enough'.

'assai' changed from the Vulgar Latin phrase 'ad satis' into Old Italian 'assai' and was later borrowed into English (mainly in musical contexts) as 'assai'.

Initially, it meant 'to a sufficient degree' (i.e. 'enough'), but over time it evolved into its current meaning of 'very' or 'exceedingly' in modern usage.