The noun song has 6 senses (first 4 from tagged texts)
1. (46) song, vocal -- (a short musical composition with words; "a successful musical must have at least three good songs")
2. (3) song -- (a distinctive or characteristic sound; "the song of bullets was in the air"; "the song of the wind"; "the wheels sang their song as the train rocketed ahead")
3. (3) song, strain -- (the act of singing; "with a shout and a song they marched up to the gates")
4. (1) birdcall, call, birdsong, song -- (the characteristic sound produced by a bird; "a bird will not learn its song unless it hears it at an early age")
5. song -- (a very small sum; "he bought it for a song")
6. Sung, Sung dynasty, Song, Song dynasty -- (the imperial dynasty of China from 960 to 1279; noted for art and literature and philosophy)