Definition: Definitions from the Official Rules of Golf appear courtesy of the USGA.
Bunker: A "bunker" is a hazard consisting of a prepared area of ground, often a hollow, from which turf or soil has been removed and replaced with sand or the like.
Grass-covered ground bordering or within a bunker, including a stacked turf face (whether grass-covered or earthen), is not part of the bunker. A wall or lip of the bunker not covered with grass is part of the bunker.
The margin of a bunker extends vertically downward, but not upward. A ball is in a bunker when it lies in or any part of it touches the bunker.
©USGA, used with permission
