Rattle means to make quick, sharp knocking sounds, like dried beans shaking inside a jar or coins jangling in your pocket. A baby's rattle makes this sound when you shake it. An old car might rattle over bumpy roads, with loose parts clanking and vibrating. Before a rattlesnake strikes, it shakes the rings of hard skin at the end of its tail, creating a distinctive buzzing rattle that warns other animals to stay away.

The word can also describe how something affects a person. When you get rattled, you become nervous, confused, or shaken up. A difficult math problem might rattle your confidence. A surprise fire drill could rattle a class that was concentrating quietly. Athletes train themselves not to get rattled by loud crowds or trash talk from opponents, staying calm and focused even when things get chaotic around them.

You can also rattle off information when you recite it quickly and easily, like rattling off all fifty state capitals without pausing to think. This usage suggests speed and confidence, with facts tumbling out one after another.