A cooler is a situation where two players hold very strong hands, and one loses despite having near‑nuts.
Explanation. Cooler comes from a chilling blow to one player’s strong hand—your monster hand meets an even bigger monster. For example, trip Kings vs straight Ace‑King on river. Both players commit because both believe they’re best. The result feels “cold” and discouraging. Coolers are rare but emotionally impactful and often unavoidable variance rather than mistake.