Sentence:  Mercer 's Whiteman association brought him into contact with Hoagy Carmichael , whose `` Snowball '' Mercer relyriced as `` Lazybones '' , in which form it became a hit and marked the real beginning of Mercer 's <WSD>song</WSD> writing career . 
Meaning of the word marked with <WSD> tags:  a short musical composition with words