'assuage' originates from Old French, specifically the word 'assouagier', ultimately from Latin elements related to 'suavis' meaning 'sweet'.

'asswaged' and Middle English forms such as 'asswagen' or 'asswage' appeared in Middle English as variants of the verb that later regularized to the modern spelling 'assuage' and its forms (assuaged, assuaging).

Initially carried a sense related to 'making sweet' or 'soothing' (from Latin 'suavis' = 'sweet'), and over time evolved into the current general sense of 'making less severe; easing or relieving'.