1.  regulator(n = noun.artifact) - any of various controls or devices for regulating or controlling fluid flow, pressure, temperature, etc.;
is a kind of control, controller
has particulars: aperture, ball cock, ballcock, draft, faucet, spigot, peg, petcock, register, escape, escape cock, escape valve, relief valve, safety valve, floodgate, head gate, penstock, sluice valve, sluicegate, water gate, thermoregulator, thermostat
Derived form verb regulate₁

2.  regulator(n = noun.person) - an official responsible for control and supervision of a particular activity or area of public interest;
is a kind of functionary, official
Derived form verb regulate₂

3.  regulator(n = noun.artifact) governor - a control that maintains a steady speed in a machine (as by controlling the supply of fuel);
is a kind of control, controller
has particulars: flywheel, timer

1.  One who, or that which, regulates. [1913 Webster]

2.  A contrivance for regulating and controlling motion [1913 Webster]

3.  A clock, or other timepiece, used as a standard of correct time. See Astronomical clock (a), under Clock. [1913 Webster]

4.  A member of a volunteer committee which, in default of the lawful authority, undertakes to preserve order and prevent crimes; also, sometimes, one of a band organized for the comission of violent crimes. [1913 Webster]
"A few stood neutral, or declared in favor of the Regulators." [1913 Webster]

growth regulator, regulator gene, voltage regulator