A fashion choice in which a woman wears a skirt (or dress) over a pair of pants or shorts.
In Anime, it's common for some girls to wear bike shorts under their skirts, the characterization usually being one of shyness or tomboyishness (athletes are popular users of this trope). See also Modesty Shorts, for when a girl wears shorts under her miniskirt to avoid Panty Shots, and Tights Under Shorts, [...] [tvtropes.org]