'atoner' originates from English, specifically from the Middle English phrase 'at one', where 'at' meant 'in/at' and 'one' meant 'united' or 'together'.

'atoner' changed from the verb 'atone' (itself from the phrase 'at one') and later the agentive suffix '-er' was added to form the noun 'atoner'.

Initially, 'atone' carried the sense 'to be at one; to reconcile', but over time it evolved into the meaning 'to make amends', and 'atoner' came to mean 'a person who makes amends'.