a person or thing that regulates something, in particular:
a person or body that supervises a particular industry or business activity:regulators of privatized utilitiesindustry 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.
Remember that the ending of regulator is spelled-or.
regulator in other Oxford dictionaries
Definition of regulator in the US English dictionary