Definitions

1. noun

The architectural framework that supports the stage of a theater or other performance space, typically including a flat or curved surface and a frame for the curtains.

“The proscenium arch added a touch of elegance to the old theater.”

2. noun

The part of a theater’s stage that is visible to the audience, typically a frame with curtains or a screen.

“The play’s setting was projected onto the proscenium.”