A drum is a musical instrument you play by striking it with your hands or sticks. Most drums are hollow cylinders with a tight material called a drumhead stretched across one or both ends. When you hit the drumhead, it vibrates and creates sound. Drums come in many sizes: small drums make higher, sharper sounds, while large drums produce deep,booming tones.

Drums are among humanity's oldest instruments, used for thousands of years in ceremonies, celebrations, and communication. In orchestras, drummers keep the rhythm and add dramatic accents. In rock bands, the drummer sits behind a drum set with multiple drums and cymbals. Traditional drums around the world include African djembes, Japanese taiko drums, and Native American powwow drums.

The word also describes a cylindrical container, like an oil drum or the rotating drum inside a washing machine. In nature, some animals drum by making repeated beating sounds: a woodpecker drums on a tree trunk, while a grouse drums its wings against the air.

When you drum your fingers on a desk, you're tapping repeatedly in a rhythm. If someone drums something into your head, they repeat it so often you can't forget it. And when a military unit drums someone out, they expel that person with ceremonial drumming, marking their disgrace.