'atomist' originates from English formation using the word 'atom' with the agent suffix '-ist'; 'atom' ultimately comes from Greek 'atomos', where 'a-' meant 'not' and 'tomos' meant 'cut' (hence 'indivisible').

'atom' changed from Greek 'atomos' to Latin 'atomus', entered Middle English as 'atom', and the agent-forming suffix '-ist' was added in English to form 'atomist'.

Initially, it meant 'one who held the doctrine that matter is composed of indivisible particles', but over time it evolved into its current meaning of 'a person who believes in or studies atoms; a proponent of atomism' (now used both historically and in scientific contexts).