/proh see"nee euhm, preuh-/ , n. , pl. proscenia /-nee euh/ . Theat.
1. Also called proscenium arch . the arch that separates a stage from the auditorium. Abbr.: pros.
2. (formerly) the apron or, esp. in ancient theater, the stage itself.
[ 1600-10; proscenium, proscaenium proskénion entrance to a tent, porch, stage (LGk: stage curtain), equiv. to pro- PRO- 2 + sken ( é ) (see SCENE) + -ion neut. n. suffix ]