Definitions for "Torch song"
a popular song with a sentimental theme of unrequited love or other form of unhappiness.
a popular song concerned with disappointment in love
A sentimental love song, usually one lamenting unrequited love. Typically (but not always) sung by women. Sondheim's classic torch song is "Losing My Mind" from Follies. Other torch songs include "As Long As He Needs Me" from Oliver! and "On My Own" from Les Miserables.