Cooler

A poker hand is considered cooler when the player has a very strong holding but loses to an even stronger hand from his opponent.

In these situations, players usually believe they will win the pot and risk their entire stack only to see that their opponent has them beaten.

For example, the most well-known preflop cooler is running pocket kings into pocket aces. Pocket kings is the second best starting hand in Texas Holdem, so you do not have any reason to believe you will be beaten. Therefore, it is considered a cooler if you are unlucky enough to run into pocket aces. In this spot, both players would have played their hands the same even if they switched positions, meaning that in the long run, you will have your fair share of coolers and also give it to other players.

Coolers are also common in postflop situations. If you flop a set versus a higher set, have the strongest full-house against the quads, or even second nut flush against a flush, all of these hands are considered coolers in poker.

It is worth mentioning that it does not mean you played the hand wrong. Quite the contrary, usually, there is nothing you can do in these situations, so you should not sweat about it and concentrate on playing your best game.