spark plug

American  

noun

spark plugs plural

1. 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.

2. Informal. a person who leads, inspires, or animates a group.

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spark plug British  

noun

1. another name for sparking plug

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spark plug Scientific  

1. 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.

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Other Word Forms

Noun Inflected Forms

• spark plugs
  plural

Etymology

Origin of spark plug

First recorded in 1900–05

Example Sentences

Know the color code Spark plug insulators are white when new.

From Time Magazine Archive

Spark plug replacement would require its removal, as the engines are quite close together.

From Time Magazine Archive

Spark plug of the Conference, and chief U.S. delegate, was public-spirited Charles Taussig, a molasses importer and economist who has labored hard & well with the Commission.

From Time Magazine Archive

Spark plug of the Conference was tireless, genial Monsignor Luigi G. Ligutti, who since January has been its first full-time executive secretary.

From Time Magazine Archive