Definition of "Song" :

noun: the act of singing

"With a shout and a song they marched up to the gates."

noun: the characteristic sound produced by a bird

"A bird will not learn its song unless it hears it at an early age."

noun: a short musical composition with words

"A successful musical must have at least three good songs."

noun: a distinctive or characteristic sound

"The song of bullets was in the air."

noun: the imperial dynasty of China from 960 to 1279; noted for art and literature and philosophy

noun: a very small sum

"He bought it for a song."