Juvenile means young or not yet fully grown, especially describing people who haven't reached adulthood yet. When police departments have a juvenile division, they work specifically with young people under 18 who break laws. A juvenile court handles cases involving minors rather than adults.

The word also describes behavior that seems childish or immature for someone's age. If a teenager starts throwing food in the cafeteria, a teacher might call that juvenile behavior because it's the kind of silly thing younger kids do. When someone acts juvenile, they're behaving less maturely than people expect.

In biology, scientists use juvenile to describe young animals or plants. A juvenile eagle doesn't have the white head feathers of an adult yet. A juvenile tree is still growing toward its full height.

When you hear juvenile, think about the space between childhood and adulthood: a juvenile isn't a little kid anymore, but isn't fully grown either. That's why we have special juvenile justice systems, recognizing that young people are still developing judgment and shouldn't always face the same consequences as adults.

As a noun, a juvenile is a young person who is not yet an adult, especially in legal settings.