spark plug
noun
a device designed to fit in each cylinder of a gasoline-powered internal-combustion engine and to produce the electric spark for igniting the mixture of gasoline and air.
Informal.
a person who leads, inspires, or animates a group.
Origin of spark plug
First recorded in 1900–05
Words nearby spark plug
spark erosion,
spark gap,
spark generator,
spark off,
spark photography,
spark plug,
spark spectrum,
spark transmitter,
spark-killer,
sparker,
sparkie
Example sentences from the Web for spark plug
British Dictionary definitions for spark plug
Scientific definitions for spark plug
spark plug
A device in the cylinder head of an internal-combustion engine that ignites the fuel mixture by means of an electric spark. Spark plugs consist of two electrodes that are separated by an insulator except at their tips. When high voltage electricity is fed to one electrode, it jumps across the gap from one tip to the other as a spark. The voltage required to generate a spark is directly proportional to the size of the gap; in a car engine it is about 18,000 volts.