king arthur 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.
a legendary king of the Britons (possibly based on a historical figure in the 6th century but the story has been retold too many times to be sure); said to have led the Knights of the Round Table at Camelot
Synonyms, antonyms and the broader and narrower relations for king arthur come from Princeton University’s WordNet. Full sources and licences.