closed shop

1. N-COUNT If a factory, shop, or other business is a closed shop, the employees must be members of a particular trade union. 衹雇傭特定工會會員的工廠、商店或企業(yè)[商業(yè)]

...the trade union which they are required to join under the closed shop agreement. …要求他們依照特定雇傭制而加入的工會。