'attainer' originates from English, formed from the verb 'attain' with the agentive suffix '-er', meaning 'one who attains'.

'attain' changed from Old French (variants attreindre/ataindre/atteindre) ultimately from Latin 'attingere' (from 'ad-' + 'tangere' meaning 'to touch'); through Middle English it became 'attain', and the agent noun 'attainer' was formed by adding '-er'.

Initially from Latin the root carried the sense 'to touch or reach'; over time the sense shifted to 'to reach or achieve (a goal)', and 'attainer' came to mean 'one who achieves or reaches'.