Cummerbund

A cummerbund or cumberbund is a broad waist sash, usually pleated, which is often worn with black tie. The cummerbund was first adopted by British military officers in colonial India and later spread to civilian use.

It means, in Hindi, waist restraint: cummer or waist + bund close, hold.

Cummerbund is also an informal word used in SCUBA to mean wide waistband on a diving stability jacket - Buoyancy Control Device - designed to provide more comfort to the user than a standard waistband and usually made of a stout fabric backed with velcro fastenings.