'atomism' originates from New Latin, specifically the word 'atomismus', derived from Greek 'atomos', where 'a-' meant 'not' and 'tomos' meant 'cut' (hence 'indivisible').

'atomism' changed from Greek 'atomos' to Late Latin/New Latin 'atomismus' and eventually became the modern English word 'atomism' (borrowed into English in discussions of ancient and early modern philosophy).

Initially, it meant 'the idea of indivisible particles' in ancient Greek thought; over time it broadened to include scientific atomic theories and figuratively any reductionist analysis of wholes into parts.