'atonalist' originates from English, specifically the word 'atonal' with the suffix '-ist', where the prefix 'a-' meant 'not' and 'tonal' is related to 'tone' (from Latin 'tonus' or Greek 'tonos').

'atonalist' was formed in English in the early 20th century by combining the adjective 'atonal' (coined to describe music without a key) with the agentive suffix '-ist'; 'atonal' itself derives via musical/linguistic usage from Greek 'tonos' through Latin 'tonus' and later European musical terminology.

Initially it meant 'not tonal' when describing music; over time it came to refer specifically to 'a person who composes, performs, or advocates atonal music.'