romanticism has 2 distinct synonyms spread across 2 of its 3 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. Its one recorded opposite is classicism.
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.
impractical romantic ideals and attitudes
a movement in literature and art during the late 18th and early 19th centuries that celebrated nature rather than civilization
“Romanticism valued imagination and emotion over rationality”
Synonyms, antonyms and the broader and narrower relations for romanticism come from Princeton University’s WordNet. Full sources and licences.