Same word as keen-witted:

active, agile, airy, alert, animate, animated, blithe, bouncy, breezy, bright, brisk, cheerful, cheery, chipper, chirpy, clever, dapper, dashing, energetic, fairylike, frolicsome, gay, good, grooving, hyper, jaunty, jolly, joyous, jumping, keen, keen-witted, light, lively, nimb