mo·tor / ˈmōtər/ • n. a machine, esp. one powered by electricity or internal combustion, that supplies motive power for a vehicle or for some other device with moving parts. ∎  a source of power, energy, or motive force: hormones are the motor of the sexual functions.• adj. 1. giving, imparting, or producing motion or action: demand is the principle motor force governing economic activity. ∎  Physiol. relating to muscular movement or the nerves activating it: the motor functions of each hand.2. chiefly Brit. driven by a motor. ∎  of or relating to motor vehicles: a dominant figure in the world of motor sports.• v. [intr.] inf. travel in a motor vehicle, typically a car or a boat: we motored along a narrow road we motored out of Breton Bay to begin our return trip down the Potomac. ∎ inf. run or move as fast as possible: he had motored along to second base on a passed ball. ∎  [tr.] chiefly Brit. convey (someone) somewhere in a motor vehicle: he hired someone to motor him back.ORIGIN: late Middle English (denoting a person who imparts motion): from Latin, literally ‘mover,’ based on movere ‘to move.’ The current sense of the noun dates from the mid 19th cent.

motor Mechanism that converts energy (such as heat or electricity) into useful work. The term is sometimes applied to the internal combustion engine, but is more often applied to the electric motor. Rocket engines are motors that can leave the Earth's atmosphere because they carry both fuel and oxidizer. Ion motors are in development, intended for spacecraft propulsion: a stream of ions, possibly from a nuclear reactor, is accelerated in a strong electrostatic field to produce a reaction that drives the spacecraft.

motor agent or force producing motion XVI; machine supplying motive power XIX. — L. mōtor (rare) mover, later in philos. use, f. mōt-, movēre MOVE; see -OR1.
Hence vb. (XIX) drive an automobile, whence motorist XIX, motorway XX.