revolving door

Từ điển Oxford Advanced Learner 8th

ˌrevolving ˈdoor [revolving door] BrE NAmE noun
1. a type of door in an entrance to a large building that turns around in a circle as people go through it
2. used to talk about a place or an organization that people enter and then leave again very quickly
•The company became a revolving-door workplace.