An engine is a machine that burns fuel to make something move. The engine in a car is the motor that makes it go.

Engines power vehicles including cars, trains, airplanes, and boats. While these engines tend to be powered by fuel that's burned, other engines get their power from electricity, which they convert to mechanical energy — fans, power tools, and small appliances all commonly have electric engines. Figuratively, you can also use the word engine to mean "something that's used to bring about a specific result." In your state, for example, tourism might be the main engine of job growth.

Definitions of engine
  1. noun
    motor that converts thermal energy to mechanical work
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    aircraft engine
    the engine that powers and aircraft
    automobile engine
    the engine that propels an automobile
    auxiliary engine, donkey engine
    (nautical) a small engine (as one used on board ships to operate a windlass)
    engine that converts mechanical energy into electrical energy by electromagnetic induction
    heat engine
    any engine that makes use of heat to do work
    reaction engine, reaction-propulsion engine
    a jet or rocket engine based on a form of aerodynamic propulsion in which the vehicle emits a high-speed stream
    an old term for an electric generator that produces alternating current (especially in automobiles)
    generator consisting of a coil (the armature) that rotates between the poles of an electromagnet (the field magnet) causing a current to flow in the armature
    external-combustion engine
    a heat engine in which ignition occurs outside the chamber (cylinder or turbine) in which heat is converted to mechanical energy
    ICE, internal-combustion engine
    a heat engine in which combustion occurs inside the engine rather than in a separate furnace; heat expands a gas that either moves a piston or turns a gas turbine
    ion engine
    a type of reaction-propulsion engine to propel rockets in space; a stream of positive ions is accelerated to a high velocity by an electric field
    jet engine
    a gas turbine produces a stream of hot gas that propels a jet plane by reaction propulsion
    magneto, magnetoelectric machine
    a small dynamo with a secondary winding that produces a high voltage enabling a spark to jump between the poles of a spark plug in a gasoline engine
    generator consisting of a steam turbine coupled to an electric generator for the production of electric power
    aerogenerator, wind generator, windmill
    generator that extracts usable energy from winds
    type of:
    machine that converts other forms of energy into mechanical energy and so imparts motion
  2. noun
    a wheeled vehicle consisting of a self-propelled engine that is used to draw trains along railway tracks
    synonyms: locomotive, locomotive engine, railway locomotive
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    a child's word for locomotive
    diesel locomotive
    a locomotive driven by a diesel engine
    dinkey, dinky
    a small locomotive
    electric locomotive
    a locomotive that is powered by an electric motor
    iron horse
    (c. 1840) an early term for a locomotive
    pilot engine
    a locomotive that precedes a train to check the track
    a small locomotive used to move cars around but not to make trips
    steam locomotive
    a locomotive powered by a steam engine
    donkey engine, switch engine
    a locomotive for switching rolling stock in a railroad yard
    tank engine, tank locomotive
    a locomotive that carries its own fuel and water; no tender is needed
    traction engine
    steam-powered locomotive for drawing heavy loads along surfaces other than tracks
    diesel-electric, diesel-electric locomotive
    a locomotive driven by the electric current generated by a diesel engine
    diesel-hydraulic, diesel-hydraulic locomotive
    a locomotive driven by a hydraulic transmission system powered by a diesel engine
    type of:
    self-propelled vehicle
    a wheeled vehicle that carries in itself a means of propulsion
  3. noun
    something used to achieve a purpose
    “an engine of change”
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    type of:
    causal agency, causal agent, cause
    any entity that produces an effect or is responsible for events or results
  4. noun
    an instrument or machine that is used in warfare, such as a battering ram, catapult, artillery piece, etc.
    “medieval engines of war”
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    battering ram
    a ram used to break down doors of fortified buildings
    arbalest, arbalist, ballista, bricole, catapult, mangonel, onager, trebuchet, trebucket
    an engine that provided medieval artillery used during sieges; a heavy war engine for hurling large stones and other missiles
    type of:
    a device that requires skill for proper use
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