What "blunder" means in chess

A blunder is a very bad move that leads to a significant loss of material, position, or the game. It is a serious mistake that weakens a player's position, leaves a piece unprotected, or creates a tactical weakness that can be exploited by the opponent. A blunder can be caused by a miscalculation, a lack of understanding of a position, or simply by overlooking a threat. It can turn a winning position into a losing one or allow the opponent to gain a decisive advantage.