/ˈproʊ.lɑːɡ/
a speech, etc. at the beginning of a play, book, or film/movie that introduces it
. [literary] an act or event that leads to a more important event
〔重大事件的〕开端，序幕:
▪ [+ to ]
a prologue to the final abandonment of trams in London
伦敦最终弃用有轨电车的序幕