In engineering, it is a device which has the function of maintaining a designated characteristic. It preforms the activity of managing or maintaining a range of value in a machine. Th measurable property of a device is managed closely by specified conditions or an advance set value or it can be a variable according to a predetermined arrangement scheme. It can be used generally to connote any set of various controls or devices for regulating or controlling items or objects.
Eamples are a voltage regulator (which is a transformer whose voltage ratio of transformation can be adjusted) and a fuel regulator (which controls the supply of fuel)
In social science, it is an official responsible for control and supervision of an activity or area of public interest.