'avoider' originates from English, formed from the verb 'avoid' + the agent suffix '-er' (meaning 'one who ...').

'avoid' came into Middle English from Old French (e.g. 'esvuidier'/'éviter'), ultimately from Latin 'vitare' meaning 'to shun'; the agent noun 'avoider' developed in English by adding '-er'.

Initially, related forms meant 'to get out of the way' or 'to shun'; over time the sense narrowed to 'to keep away from, to refrain from' and the agent form came to mean 'one who avoids'.