JK Share definition Flag High school girl. Comes from “Joshi Kohsei” in Japanese. “Joshi” means “girl”, and “Kohsei” is an alternative form of “Kohkohsei” which means “high school student”. JK is cute. JK by sb0 September 21, 2019 0 0 Get merch Get the JK mug. Buy Now — $32.95 See more merch