atomism Meaning, Definition & Usage

1. noun (psychology) a theory that reduces all mental phenomena to simple elements (sensations and feelings) that form complex ideas by association
   
2. noun (chemistry) any theory in which all matter is composed of tiny discrete finite indivisible indestructible particles
   atomic theory; atomist theory; atomistic theory.
   
   • the ancient Greek philosophers Democritus and Epicurus held atomic theories of the universe

WordNet