Blocker
A card in your hand that reduces the number of ways an opponent can hold a specific hand. Holding the ace of spades on a three-spade board 'blocks' the nut flush.
Frequently asked questions
What is a blocker in poker?
A card you hold that an opponent therefore cannot, which removes combinations from their range. Holding the ace of hearts on a three-heart board blocks every nut-flush combination they could have.
How do blockers change a decision?
They make the same bet work more often. Bluffing with a hand that blocks the nuts means fewer of the opponent's calling hands exist — so blockers are the standard way of choosing which of several equally weak hands to bluff with.
Where do blockers matter most?
On the river, where no cards are left to come and the ranges are fixed, and in preflop four-bet bluffing, where an ace or king in hand cuts the premium combinations the opponent can continue with. On early streets their effect is real but small.