A corset is a fitted garment with stiff supports that cinch in the waist of the person who's wearing it. Corsets can be worn for back support, but women used to wear them to look skinny in their dresses.
Historians believe that corsets have been around for more than three hundred years. As fashion has changed over time, the shape and construction of corsets has also changed — today, while corsets are mainly worn as costumes or for medical reasons, many women still wear "foundation garments," which differ from corsets only in material — the modern version is made of stretchy fabric rather than stiff bones or metal. Corset is an Old French word, from cors, or "body."