waist bow
A bow that is tied around the front side of a character's waist. It should function as a makeshift belt to keep the dress around the waist. If the bow is a decorative aspect of the clothing, use dress bow instead (unless both are present).
If the bow is in the rear, use back bow instead. There are instances of both happening however, such as post #3495784.
See also
This tag implicates bow (learn more).