Burst means to break open suddenly and violently, usually from pressure building up inside. When you blow too much air into a balloon, it bursts with a loud pop. A water pipe can burst in freezing weather when ice forms inside and expands. When something bursts, it doesn't just crack or leak: it ruptures all at once, often releasing whatever was contained inside.

The word also describes sudden, forceful action. A runner might burst through the finish line, meaning they came through with sudden speed and energy. Laughter can burst from someone who's been trying to hold it in. Students might burst into a classroom, flinging the door open and rushing inside. Light can burst through clouds after a storm.

When used this way, burst captures that sense of explosive release: something held back that suddenly comes rushing out all at once. You might feel ready to burst with excitement before opening birthday presents, or burst into tears after holding your feelings in too long. A burst of speed means a sudden increase in how fast you're moving. The word always suggests intensity and suddenness, whether something is literally breaking apart or figuratively exploding into action.