Unblocker
Also: unblocking
A card in your hand that leaves the hands you want an opponent to hold available to them. When bluffing, you want unblockers to their folding range — cards that do not remove the weak hands you are trying to fold out.
Blockers get all the attention, but the reverse question is just as important. If you bluff the river holding a card that removes most of an opponent's missed draws, you have made it more likely they hold a hand that calls. The strongest bluffing hands usually block their calling range and unblock their folding range at once.
In practice the effect is small on any single hand and substantial across thousands, which is why it surfaces in solver work far more often than at the table.
Related terms
Full glossaryFrequently asked questions
What is the difference between a blocker and an unblocker?
A blocker removes hands from your opponent's range; an unblocker deliberately does not, keeping the hands you want them to fold in play.