Play that has only one act, as distinct from plays that occur over several acts
A one-act play is a play that has only one act, as distinct from plays that occur over several acts. One-act plays may consist of one or more scenes. The 20-40 minute play has emerged as a popular subgenre of the one-act play, especially in writing competitions. One act plays make up the overwhelming majority of Fringe Festival shows including at the Edinburgh Fringe Festival. Wikipedia