Collins COBUILD Advanced Learner's English Dictionary - revolving door

(revolving doors) 1. Some large buildings have revolving doors instead of an ordinary door. They consist of four glass doors which turn together in a circle around a vertical post. As he went through the revolving doors he felt his courage deserting him. N-COUNT: usu pl 2. When you talk about a revolving door, you mean a situation in which the employees or owners of an organization keep changing. They have accepted an offer from another firm with a busy revolving door. N-COUNT: usu sing c darkgreen]disapproval