joint chiefs of staff has 1 distinct synonym spread across 1 of its 1 sense. 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.
the executive agency that advises the President on military questions; composed of the chiefs of the United States Army and the United States Navy and the United States Air Force and the commandant of the United States Marine Corps
Synonyms, antonyms and the broader and narrower relations for joint chiefs of staff come from Princeton University’s WordNet. Full sources and licences.