cur·tain-rais·er
noun/ˈkɜːtn reɪzə(r)/
/ˈkɜːrtn reɪzər/
- curtain-raiser (to something) a small event that prepares for a more important one
（重大事件的）前奏，序曲 - curtain-raiser (to something) a short performance before the main performance in a theatre, etc.
（剧院等主要剧目演出前的）序幕，开场小戏
Word Originlate 19th cent.: originally used in the theatre to denote a short opening piece performed before a play.