·noun One who, or that which, regulates.
II. Regulator ·noun A clock, or other timepiece, used as a standard of correct time. ·see Astronomical clock (a), under Clock.
III. Regulator ·noun 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.
IV. Regulator ·noun A contrivance for regulating and controlling motion, as: (a) The lever or index in a watch, which controls the effective length of the hairspring, and thus regulates the vibrations of the balance. (b) The governor of a steam engine. (c) A valve for controlling the admission of steam to the steam chest, in a locomotive.