In poker, a “cooler” refers to a situation where a player has a strong hand, but it loses to an even stronger hand. It usually happens when two players have hands that are very strong but one is just slightly stronger than the other.
For example, if one player has a set of kings, and the other player has a set of aces, the player with kings is said to have been “cooled.” The term “cooler” is often used to describe a situation that is outside of a player’s control, as opposed to a bad beat, which refers to a situation where a player loses despite having the best hand.