To be sprightly is to be full of youthful, vibrant energy. You don’t have to be young to be sprightly, though, energetic old people can be sprightly, too. Weeeeeee!
The word sprightly comes from the word sprite, which is a small, elf-like fairy creature. If someone acts like a happy little fairy, has a lot of enthusiasm, and acts in a youthful way, she’s sprightly. To be sprightly is to be full of spirit and vitality, to be happy, and to have a positive attitude. Someone who radiates energy and positivity is sprightly.