rock'n'roll has 5 distinct synonyms 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 genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western
“rock is a generic term for the range of styles that evolved out of rock'n'roll.”
Synonyms, antonyms and the broader and narrower relations for rock'n'roll come from Princeton University’s WordNet. Full sources and licences.