backroom

UK: /ˈbækrʊm/

WordReference Random House Unabridged Dictionary of American English © 2026

back′ room′, 

1. a room located in the rear, esp. one used only by certain people.
2. British Terms a place where powerful or influential persons, esp. politicians, meet to plan secretly or from which they exercise control in an indirect manner:
   The candidate for mayor was chosen in the precincts' back rooms.
Also, back′room′. 
• 1585–95

Collins Concise English Dictionary © HarperCollins Publishers::

back room noun

1. a place where research or planning is done, esp secret research in wartime
2. (as modifier): back-room boys