Corset belt
From wipipedia.org
A corset belt is a very wide belt that can be pulled very tight, thus acting as a sort of corset. It is generally worn over clothing, hence used as an ornament as well as a corset.
It differs from a waist cinch or short corset in that it buckles up (with a very large buckle, or multiple buckles on narrow straps across the front) rather than lacing up.