stage door
noun [ C ] uk/ˌsteɪdʒ ˈdɔːr/ us/ˌsteɪdʒ ˈdɔːr/
（供演职人员进出的）剧场后门
the door that is used by the actors and theatre workers when entering and leaving the theatre
We stood by the stage door waiting to get the actors' autographs. 我们在剧场后门等着要演员的签名。