micro shorts
A pair of shorts that are so small that they could easily be mistaken for panties.
Micro shorts can be both regular outerwear or an undergarment. They are also sometimes worn as bikini shorts.
As underwear, they can be worn over panties as loungewear, as undershorts under a skirt, or as shorts-shape underpants directly in lieu of panties. As panty alternative, micro shorts are usually known as "boyshorts".
If the leg parts are very short but loose it should probably be short shorts instead.