Hyper means excessively energetic, excitable, or active. When someone acts hyper, they might bounce around, talk rapidly, or struggle to sit still. A kid who's hyper at a birthday party might run from activity to activity without stopping, unable to focus because of all the excitement and energy.

When you add hyper to other words, it intensifies their meaning: hyperactive means extremely active, hypersensitive means overly sensitive, and hyperaware means unusually alert to everything around you.

While being energetic is often positive, hyper usually suggests too much of a good thing. A dog who's hyper might jump on everyone and knock things over. A hyper student might have trouble paying attention in class because their energy makes it hard to concentrate. Parents sometimes notice their children get hyper after eating lots of sugar or when they're overtired and wound up instead of sleepy.

The word works as an adjective (“She felt hyper after drinking two sodas”) and as a prefix you can add to many words to mean “extremely” or “too much.”