When the stomach is partially exposed by clothing.
The midriff is the region of the body between the chest and the waist. Use this tag when there are clothes above (e.g. a crop top) and below (e.g. pants, shorts, skirt), but the stomach is bare or visible beneath see-through clothing.
Don't use this tag if the character is topless, bottomless, nude, or wearing underwear only or a bikini only. It may be used for underwear worn as outerwear, such as for sports bras, camisoles or tank tops worn with panties, or other similar outfits.
Often goes with navel and stomach.