song has 8 distinct synonyms spread across 4 of its 6 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 short musical composition with words
“a successful musical must have at least three good songs”
a distinctive or characteristic sound
“the song of bullets was in the air”
the act of singing
“with a shout and a song they marched up to the gates”
the characteristic sound produced by a bird
“a bird will not learn its song unless it hears it at an early age”
a very small sum
“he bought it for a song”
the imperial dynasty of China from 960 to 1279; noted for art and literature and philosophy
Synonyms, antonyms and the broader and narrower relations for song come from Princeton University’s WordNet. Full sources and licences.