[ at-uh-miz-uhm ]

  1. Also called atomic theory. Philosophy. the theory that minute, discrete, finite, and indivisible elements are the ultimate constituents of all matter.

  2. Psychology. a method or theory that reduces all psychological phenomena to simple elements.

Origin of atomism

First recorded in 1670–80

Other words from atomism

  • at·om·ist, noun
  • at·om·is·tic, at·om·is·ti·cal, adjective
  • at·om·is·ti·cal·ly, adverb

Words Nearby atomism Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use atomism in a sentence

British Dictionary definitions for atomism


/ (ˈætəˌmɪzəm) /

  1. an ancient philosophical theory, developed by Democritus and expounded by Lucretius, that the ultimate constituents of the universe are atoms: See atom (def. 3)

    • any of a number of theories that hold that some objects or phenomena can be explained as constructed out of a small number of distinct types of simple indivisible entities

    • any theory that holds that an understanding of the parts is logically prior to an understanding of the whole: Compare holism (def. 3)

  1. psychol the theory that experiences and mental states are composed of elementary units

Derived forms of atomism

  • atomist, noun, adjective
  • atomistic or atomistical, adjective
  • atomistically, adverb

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012