Definition from Wiktionary, the free dictionary
From the attitude necessary in the game of poker, since one is ill-advised to reveal delight at being dealt a winning hand lest other players decline to bet (or contrariwise, show disappointment at a poor hand if one is inclined to bluff).
- Wearing a poker face: studiously neutral in facial expression; giving nothing away.
- John, in his most poker-faced manner, continued to explain the rules.
- poker-faced at OneLook Dictionary Search