vietnam has 4 distinct synonyms spread across 2 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.
a communist state in Indochina on the South China Sea; achieved independence from France in 1945
a prolonged war (1954-1975) between the communist armies of North Vietnam who were supported by the Chinese and the armies of South Vietnam who were supported by the United States
Synonyms, antonyms and the broader and narrower relations for vietnam come from Princeton University’s WordNet. Full sources and licences.