'anoil' originates from the English prefix 'a-' (a- meaning 'on' or 'to') combined with the noun 'oil', where 'oil' comes via Old French 'oile' from Latin 'oleum'.

'anoil' appeared in Middle English in forms such as 'anoilen' or 'an-oil' as a verbal formation meaning 'to put oil on', and over time the form settled as the modern spelling 'anoil'.

Initially it meant 'to put oil on or to grease', and over time it retained that basic sense but became less common and somewhat archaic, often replaced by 'anoint' or 'oil' in modern usage.