From Longman Dictionary of Contemporary Englishstage doorˌstage ˈdoor noun [countable usually singular] APTthe side or back entrance to a theatre, used by actors and theatre workers
Examples from the Corpus
stage door• He stopped by on his night off, was let in the stage door, and stood in the wings.• Just before I turned into the stage door, I passed Charles Fox, the theatre make-up shop.• He heard a thunk as some one hit the crush bar on the inside of the stage door.• Eliza went out the stage door into the alley.• Musicians were so desperate to hear Michelangeli that they borrowed violin cases and sneaked in through the stage door.• Cards and flowers had already come to the stage door, and Bernie was making mocking remarks at every opportunity.• He received it the next morning when he took his usual letter to the stage door.• Before each performance, he slid casually through an unnoticeable stage door into a world unknown to most. 