Definition: Definitions from the Official Rules of Golf appear courtesy of the USGA.
Casual Water: "Casual water" is any temporary accumulation of water on the course, that is visible before or after the player takes his stance, and is not in a water hazard. Snow and natural ice, other than frost, are either casual water or loose impediments, at the option of the player. Manufactured ice is an obstruction. Dew and frost are not casual water. A ball is in casual water when it lies in or any part of it touches the casual water.
©USGA, used with permission
