The term DEVICE TO REGULATE FLOW can be summarized as a VALVE, which is a five-letter word. A VALVE is a device that controls the flow of liquids or gases in a system. Valves are used in a variety of applications, such as controlling the flow of water in a plumbing system, regulating the pressure of steam in a boiler, or controlling the flow of air in an air conditioning system. Valves are also used in industrial processes to control the flow of chemicals and other substances.