B-side

US /ˈbiː.saɪd/
UK /ˈbiː.saɪd/
"B-side" picture
1.

B面, 副歌

a secondary song on a vinyl single, typically less prominent than the A-side

:
Many classic rock bands released some of their best material as B-sides.
許多經典搖滾樂隊將他們的一些最佳作品作為B面歌曲發行。
The song on the B-side became a surprise hit.
B面的歌曲意外走紅。