closed shop

US: /ˈklɔʊzd ˈʃɑp/

WordReference Random House Learner's Dictionary of American English © 2025

closed shop /ˈklɔʊzd ˈʃɑp/  n. [countable]

1. a business in which union membership is a condition of employment.

WordReference Random House Unabridged Dictionary of American English © 2025

closed′ shop′, 

1. a factory, office, or other business establishment in which union membership is a condition of being hired as well as of continued employment. Cf. open shop.

• 1900–05, American.

Collins Concise English Dictionary © HarperCollins Publishers::

closed shop noun

1. (formerly) an industrial establishment in which there exists a contract between a trade union and the employer permitting the employment of the union's members only
   Compare open shop