'assuage' originates from Old French, specifically the word 'assouagier', where the prefix 'as-' (from Latin 'ad') meant 'to' and the root related to 'suavis' meant 'sweet' or 'pleasant'.

'assuage' changed from Old French 'assouagier' (also recorded as 'asouagier') into Middle English forms such as 'asswage'/'aswage' and eventually became the modern English word 'assuage'.

Initially, it meant 'to make sweet or soften', but over time it evolved into its current meaning of 'to lessen the intensity of something (pain, grief) or to satisfy a desire/conscience'.