A cummerbund is a broad, pleated waistband made of satin, worn with men's formal wear and tuxedos worn in place of a vest or waistcoat.
The form of the cummerbund is a wide band around the waist. It was first adopted by British military officers in colonial India as an alternative to the waistcoat. Once it was adopted as civilian dress, it was restricted to the narrow range of colors which accompany black tie. The pleats face up because they were originally used to hold ticket stubs and similar items, hence the nickname crumb-catcher. Modern use of the cummerbund provides transition between the shirt and the waistband.The fastening is adjustable around the back and held shut by a buckle.