Song

 1. a short metrical composition intended or adapted for singing, esp. one in rhymed stanzas; a lyric; a ballad.  

2. a musical piece adapted for singing or simulating a piece to be sung: Mendelssohn's “Songs without Words.”  

3. poetical composition; poetry.  

4. the art or act of singing; vocal music.  

5. something that is sung.  

6. an elaborate vocal signal produced by an animal, as the distinctive sounds produced by certain birds, frogs, etc., in a courtship or territorial display.