A waistcoat (UK and Commonwealth, or ; colloquially called a weskit) or vest (US and Canada) is a sleeveless upper-body garment. It is usually worn over a dress shirt and necktie and below a coat as a part of most men's formal wear. It is also sported as the third piece in the traditional three-piece male suit. Any given waistcoat can be simple or ornate, or for leisure or luxury. Historically, the waistcoat can be worn either in the place of, or underneath, a larger coat, dependent upon the weather, wearer, and setting.
Daytime formal wear and semi-formal wear commonly comprises a contrastingly coloured waistcoat, such as in buff or dove gray, still seen in morning dress and black lounge suit. Traditionally, a white waistcoat is worn for white tie and a black one for black tie.