united states waters 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.
territorial waters included within a distance of 12 nautical miles of the coasts of the United States and its territories
“ships operating in United States waters must adhere to United States laws and regulations”
Synonyms, antonyms and the broader and narrower relations for united states waters come from Princeton University’s WordNet. Full sources and licences.