'appease' originates from Old French, specifically the word 'apaiser' (also attested as 'apaisier'), where the root 'pais' (from Latin 'pax') meant 'peace'.

'appease' changed from Old French 'apaiser' into Middle English forms such as 'appaisen'/'appeasen' and eventually became the modern English verb 'appease'; the noun 'appeaser' was formed by adding the agentive suffix '-er'.

Initially it meant 'to bring to peace' or 'to make peace'; over time it broadened to mean 'to pacify or placate (sometimes by making concessions)', and in political contexts acquired a sometimes negative sense of conceding to aggression.