Energetic describes someone who has lots of get-up-and-go. When you decide to jog alongside the bus instead of taking it to work, you are energetic — so energetic that it tires the rest of the commuters out just watching you.
Energetic comes from the Greek, energetikos, meaning “active.” When you are energetic, you're active with enthusiasm and excitement to spare. Energetic describes those little kids you babysit, who never sit still and force you to play hide and seek. Energetic can also mean a powerful focused effort, where you work hard to achieve something. The energetic bond between the men was formed after months of training together in the military.