Crossword clues for the word: ATOMISM The word ATOMISM has appeared as an answer to at least 7 crossword clues on different crossword puzzles. Crossword clues for ATOMISM Showing 1 to 7 of 7 results Clue(s) "Theory that answers the question ""What's the matter?""?" Belief that all things are made of particles Lucretius's theory Particle theory Particle-based philosophy Philosophical theory first advanced by Leucippus and Democritus Theory on makeup of universe.