smoke-filled room

plural smoke-filled rooms

1. idiomaticA place where powerful people meet to decide a matter in secret, often of a political nature.

   Near-synonym: backroom (as a meeting place of crooked insiders)

   2 more examples

   In its first decade, prize business was settled in the smoke-filled rooms of London clubs, where it remained resolutely insular.

   2009, Robert McCrum, “No Tóibín, no Trevor? Yes, it's time for more Booker controversy”, in The Guardian

   If the forums in which we make this case consist of the smoke-filled rooms of Washington, the votes aren't there.

   2013, Ted Cruz, “Ted Cruz Punches Back”, in National Review

   Synonyms: backroom[insider]]s>

2. Used other than figuratively or idiomatically: see smoke, filled, room.