'appeasive' originates from the adjective-forming suffix '-ive' added to the verb 'appease', where 'appease' comes from Old French 'apaisier' (also spelled 'apaisier/apaiser'), ultimately from Vulgar Latin *pacare based on Latin 'pax, pac-' meaning 'peace'.

'appease' changed from Old French 'apaisier' and entered Middle English as 'apaisen'/'appeasen', and the modern English adjective 'appeasive' was formed by adding '-ive' to 'appease'.

Initially it meant 'to make peaceful' or 'to bring to peace', and over time the sense shifted to 'to placate or conciliate', yielding 'appeasive' meaning 'intended to placate or calm'.