Other forms: coltishly
An energetic, playful person can be described as coltish. A coltish preschooler might skip happily across the room and then slide to a stop in her socks.
There's something a little young and awkward implied in the word coltish, which arose in the 14th century from the sense of a colt, or young horse, as a lively, frolicking, long-legged creature. Skinny-legged teenagers dashing around a mall are coltish, and a soccer team of five year-olds is made up of happy, coltish players.