1911 Encyclopædia Britannica/Proscenium

PROSCENIUM (Gr. προσκήνιον), that part of the stage in the ancient Greek theatre which lies in front of the σκηνή, scena, the back wall; the word appears to embrace the whole stage between the ὀρχήστρα and the σκηνή. In the modern theatre the word is applied to that part of the stage which is in front of the curtain and the orchestra, and sometimes to the whole front of the stage, including the curtain and the arch containing it, which separates the stage from the auditorium.