drop waist 
(also dropped waist)
noun
A style of waistline on a dress cut so that the seam is positioned at the hips rather than the waist.Avoid any styles with a drop waist, which adds length to the torso....
- Features include two outer pockets, an inner security pocket, a rollaway hood, Velcro cuffs, and a lower-back drop waist.
- With very little thought as to what to wear, Adaela dressed in a light colored dress, sort of a dawn pink that had a dropped waist, rounded neckline, and sleeves that fluttered from the elbow.