[pro.logue] also pro.log n [ME prolog, fr. MF prologue, fr. L prologus preface to a play, fr. Gk prologos part of a Greek play preceding the entry of the chorus, fr. pro- before + legein to speak--more at pro-, legend] (14c) 1: the preface or introduction to a literary work
2. a: a speech often in verse addressed to the audience by an actor at the beginning of a play b: the actor speaking such a prologue
3: an introductory or preceding event or development