To muff means to handle something clumsily or mess up a task that should have been straightforward. When a baseball player muffs an easy catch, the ball bounces right out of their glove even though they were in perfect position. When an actor muffs their lines during a play, they forget words they've rehearsed dozens of times.

The word suggests a mistake that's particularly frustrating because it seemed simple or well within someone's abilities. You might muff an easy quiz question you actually knew the answer to, or muff your chance to make a good impression by accidentally spilling juice on yourself.

Muff often appears with words like “chance” or “opportunity”: someone might muff their chance to score the winning goal by shooting wide, or muff an opportunity to speak up by staying silent when they had something important to say.