My favorite:
"vomitorium"
These are entrances through the audience that are specifically constructed into the theatre. The Beaumont and the Newhouse at Lincoln Center have these. Most theatres do not.
They are not entrances and/or exits made in the aisles of the theatre like Mama Rose's first entrance and Billy Elliot's last exit.
I believe the term comes from the ancient Greeks or Romans.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher