To stammer means to speak with sudden stops, repeated sounds, or difficulty getting words out smoothly. When someone stammers, they might say “I-I-I want to go” instead of “I want to go,” or they might get stuck on the first sound of a word and have trouble pushing past it.

Stammering often happens when someone feels nervous, embarrassed, or put on the spot. You might stammer when called on unexpectedly in class, or when meeting someone you admire. Some people stammer only in stressful moments, while others stammer as a regular part of how they speak, regardless of how they feel.

The word stutter means almost exactly the same thing as stammer, and most people use them interchangeably. Both words can be nouns too: “She has a stammer” or “He spoke with a stutter.”

Stammering doesn't mean someone is confused or doesn't know what they want to say. Their brain knows the words perfectly well, but the physical act of speaking trips them up. Many successful people throughout history have stammered, including King George VI of England, whose struggle to manage his stammer became famous through the movie The King's Speech.