Portal

A framed opening the audience looks through, often repeated down the stage to build depth.

DesignersCrew

False prosceniumA frame built inside the real proscenium arch to make the opening smaller or give it a new look for one show.
MaskingBlack curtains or flats that hide the wings, the lights and the backstage from the audience.
LegsTall, narrow curtains hung at the sides of the stage to hide the wings from the audience.

More in The stage

Stage left Stage right Upstage Downstage Centre stage Apron