'atter' originates from Old English, specifically the word 'atter', where 'atter' meant 'poison'.

'atter' changed from Old English 'atter' into Middle English 'ater' and eventually became largely obsolete in Modern English, surviving mainly in compounds such as 'attercop'.

Initially, it meant 'poison', but over time it fell out of general use and is now preserved chiefly in certain compounds and dialectal usages.