To bluff means to pretend you're in a stronger position than you really are, hoping others will believe you. In poker, a player might bluff by betting confidently on weak cards, trying to convince opponents to fold better hands. A basketball player might fake a move to make a defender go the wrong way. Someone cornered by a bully might bluff courage they don't feel, standing tall and speaking firmly to avoid a fight.

Bluffing works when you're convincing: your face, voice, and actions all have to match your pretend confidence. Good bluffs depend on what others believe, not what's actually true. A chess player who acts bored might bluff their opponent into thinking they've already won. But if someone calls your bluff, they challenge you to prove your claims, which can reveal you were faking.

As a noun, a bluff can also mean a steep cliff or headland, usually overlooking water.