Wordnet 3.0
NOUN (1)
1. 
 (chemistry) any theory in which all matter is composed of tiny discrete finite indivisible indestructible particles; 
- Example: "the ancient Greek philosophers Democritus and Epicurus held atomic theories of the universe"[syn: atomism, atomic theory, atomist theory, atomistic theory]
WordNet (r) 3.0 (2006):
atomistic theory
    n 1: (chemistry) any theory in which all matter is composed of
         tiny discrete finite indivisible indestructible particles;
         "the ancient Greek philosophers Democritus and Epicurus
         held atomic theories of the universe" [syn: atomism,
         atomic theory, atomist theory, atomistic theory]
         [ant: holism, holistic theory]