Definition: Definitions from the Official Rules of Golf appear courtesy of the USGA.
Hole: The "hole" must be 4 1/4 inches (108 mm) in diameter and at least 4 inches (101.6 mm) deep. If a lining is used, it must be sunk at least 1 inch (25.4 mm) below the putting green surface unless the nature of the soil makes it impracticable to do so; its outer diameter must not exceed 4 1/4 inches (108 mm).
©USGA, used with permission
