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waiting room; anteroom; antechamber; green room
出番を待つ出演者たちが控え室で談笑していた。
The performers waiting for their turn were chatting in the green room.
面接の前に控え室で書類の最終確認をした。
I did a final check of the documents in the waiting room before the interview.
控え室にはお茶とお菓子が用意されていた。
Tea and sweets had been prepared in the anteroom.