naturalism has 1 distinct synonym spread across 1 of its 2 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
(philosophy) the doctrine that the world can be understood in scientific terms without recourse to spiritual or supernatural explanations
an artistic movement in 19th century France; artists and writers strove for detailed realistic and factual description
Synonyms, antonyms and the broader and narrower relations for naturalism come from Princeton University’s WordNet. Full sources and licences.