regulator

noun

• a person or thing that regulates something, in particular:
• a person or body that supervises a particular industry or business activity: regulators of privatized utilities industry regulators
• a device for controlling the rate of working of machinery or for controlling fluid flow, in particular a handle controlling the supply of steam to the cylinders of a steam engine: the driver had opened the regulator to ease forward [as modifier]:a speed regulator
• a device for adjusting the balance of a clock or watch in order to regulate its speed.