internationalism 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. Its one recorded opposite is nationalism.
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.
the doctrine that nations should cooperate because their common interests are more important than their differences
quality of being international in scope
“he applauded the internationality of scientific terminology”
Synonyms, antonyms and the broader and narrower relations for internationalism come from Princeton University’s WordNet. Full sources and licences.