theme song

theme-song的词性：
n.Music （名词）【音乐】

1. An often repeated song in a musical play that is identified with the work or one of its characters.
主题歌：音乐剧中与行为或角色之一有关的经常重复的歌曲

2. A song that is identified with a performer, group, or radio or television program.
主打歌：与表演者，小组或收音机节目或电视节目有关的歌