pietism has 3 distinct synonyms 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.
17th and 18th-century German movement in the Lutheran Church stressing personal piety and devotion
Synonyms, antonyms and the broader and narrower relations for pietism come from Princeton University’s WordNet. Full sources and licences.