song 
/ˈsɑ:ŋ/ noun
plural songs /ˈsɑ:ŋ/ noun 1 [count] : a short piece of music with words that are sung
▪ He sang a love song. ▪ The song was playing on the radio. — see also folk song, siren song, swan song, theme song, torch song 2 [noncount] : the act of singing
▪ She suddenly burst/broke into song. [=began singing] ▪ The event was celebrated in song by a folk group. 3 [count, noncount] : a series of musical sounds that are produced by a bird or an animal (such as a whale)
▪ I could hear the song of a sparrow.
▪ He sang a love song. ▪ The song was playing on the radio. — see also folk song, siren song, swan song, theme song, torch song
▪ She suddenly burst/broke into song. [=began singing] ▪ The event was celebrated in song by a folk group.
▪ I could hear the song of a sparrow.
for a song
chiefly US, informal : for a very small amount of money
▪ This old car can be bought/had for a song.
▪ This old car can be bought/had for a song.
