- a series or group of three plays, novels, operas, etc., that, although individually complete, are closely related in theme, sequence, or the like.
- (in ancient Greek drama) a series of three complete and usually related tragedies performed at the festival of Dionysus and forming a tetralogy with the satyr play.
- a group of three related things.
- a series of three related works, esp in literature, etc
- (in ancient Greece) a series of three tragedies performed together at the Dionysian festivals
