n. introduction, usually to a poem or play
In the prologue to Romeo and Juliet, Shakespeare introduces the audience to the feud between the Montagues and the Capulets.
Sentence in Classic:
The fire soon flared up the chimney, giving the room an appearance of comfort that was doubled by contrast with the drumming of the storm without, which snapped at the windowpanes and breathed into the chimney strange low utterances that seemed to be the prologue to some tragedy.
Return of the Native By Thomas Hardy Context