a person or thing that regulates.

Horology .

an adjustable device in a clock or a watch for making it go faster or slower.

a master clock, usually of great accuracy, against which other clocks are checked.

Machinery .

a governor mechanism for regulating the flow of fuel, steam, etc., to an engine in order to maintain constant speed under varying load or resistance.

a valve for regulating the pressure of flowing gas or liquid to maintain a predetermined pressure.

any of various mechanisms for maintaining a temperature, a level of liquid in a tank, etc.

Electricity . a device for maintaining a designated characteristic, as voltage or current, at a predetermined value, or for varying it according to a predetermined plan.

a device on scuba equipment for regulating the rate at which compressed air is fed through a breathing tube in proportion to the depth of water.

a device for maintaining a constant gas pressure.

( initial capital letter ) American History .

a member of any of several bands or committees in North Carolina (1767?71), formed to resist certain abuses, as extortion by officials.

(in newly settled areas) a member of any band or committee organized to preserve order before the establishment of regular legal authority.

noun

director , governor , manager , switch , thermostat , valve