An impassive facial expression cultivated to prevent other players from determining whether one's actions in the game are the result of a quality hand, or of bluffing
Though he thought he had a perfect poker face, he had a number of tells his opponents soon learned.
Any similar expression used to prevent giving away one's motives, feelings, or situation
A poker face is an expression on your face that shows none of your feelings. In business a poker face can be very useful She managed to keep a poker face