'benison' originates from Old French, specifically the word 'benison', ultimately from Latin 'benedictio', where 'bene-' meant 'well' and 'dicere' meant 'to speak.'

'benison' changed from Old French word 'benison' (via Anglo-French) and from Latin 'benedictio', and eventually became the modern English word 'benison'.

Initially, it meant 'a blessing' (a speaking of good); over time it retained this sense but became rarer and more literary/archaic in everyday use.