pluralism has no recorded synonym. 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 monism.
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.
a social organization in which diversity of racial or religious or ethnic or cultural groups is tolerated
the doctrine that reality consists of several basic substances or elements
Synonyms, antonyms and the broader and narrower relations for pluralism come from Princeton University’s WordNet. Full sources and licences.
the practice of one person holding more than one benefice at a time