'assoil' originates from Old French, specifically the word 'assouillier' (related forms 'assolver'/'assoudre'), where the element 'solver' (from Latin 'solvere') meant 'to loosen, release'.

'assoil' changed from Middle English forms such as 'assoylen'/'assolen', borrowed from Old French (related to 'assouillier' or variants of 'ad-solvere'), and eventually became the modern English word 'assoil'.

Initially, it meant 'to loosen or release (a debt or obligation)' in a more general or literal sense, but over time it evolved into the current meaning 'to absolve or pardon (someone)'.