A dumpy level is a precision optical instrument used in surveying and construction to measure horizontal levels and establish elevations. It consists of a telescope mounted on a stable base that can rotate 360 degrees, allowing for accurate sighting of reference points. Commonly used for tasks such as setting out levels, transferring heights, and checking foundations, the dumpy level is known for its durability and ease of use. It requires a tripod for stability and works in conjunction with a leveling staff to provide accurate readings on construction sites.