āmēnäⁿsəgrēz noun
( plural éminences grises “)
Etymology: French, literally, gray eminence, nickname of Père Joseph (François Le Clerc du Tremblay) died 1638 French monk and diplomat who was confidant of Cardinal Richelieu died 1642 French statesman and cardinal who was styled Éminence Rouge red eminence; from the colors of their respective habits
: a confidential agent ; especially : one exercising unsuspected or unofficial power