A basque is a close-fitting bodice, extending from the shoulders to approximately waist level. It may have attached suspenders, and is often worn with a matching pair of knickers or a thong.
Unlike a corset, it is not designed to constrain the figure.
Basques are usually made of satin, but may be in a wide range of materials, such as PVC or see-through nylon. Sometimes they have a mixture of areas, opaque over the breasts and see-through in most other places.