speakeasy

noun

1. (historical)An illegal saloon or tavern, especially one operated during the American Prohibition period in the 1920s.

   “Many of the legitimate nightclubs of today sprang like legalized phoenixes from the still-hot ashes of the speakeasies of prohibition days.”

   “Retuning^([sic]) to Gotham, he came to intimately know Manhattan's speakeasy scene. “At a speakeasy,” Hirschfeld acknowledged, “you had to be known to get in...each place had its own clientele.” Membership cards, really fake IDs, were common.”