The stage area between the curtain and the orchestra.
The stage area immediately in front of the scene building.
The row of columns at the front of the scene building, at first directly behind the circular orchestra but later upon a stage.
A proscenium arch.
Pronounced as (IPA)
/pɹəʊˈsiː.ni.əm/
Etymology
From Latin proscaenium (“in front of the scenery”), from Ancient Greek προσκήνιον (proskḗnion), from πρό (pró, “before”) + σκηνή (skēnḗ, “scene building”).