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Definition of spark plug

spark plug

(UK: sparking plug)
Plural:spark plugs
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spark plug Lexical Profile

• noun

1

A device fitted into the cylinder head of an internal-combustion engine that ignites the compressed fuel-air mixture by means of an electric spark.

Example

"The mechanic replaced a fouled spark plug to resolve the engine's persistent misfire."

2

A highly energetic or motivating person who inspires others and drives a group or project forward.

Example

"As the captain of the team, she was the spark plug who kept everyone's spirits high during difficult matches."

Synonyms
View all synonyms for spark plug

• Nearby Words

sparaxis
sparerib
sparganium
spark plug
sparkleberry
sparmannia
sparrow

Word Origin & Etymology

Coined in the early 20th century during the development of internal combustion engines, combining 'spark' (Old English 'spearca') and 'plug' (Middle Dutch 'plugge'). The metaphorical sense referring to an energetic, motivating person emerged in American English around the 1930s.

Cite this Entry

Wordmom. (2026). Definition of Spark plug. In Wordmom Dictionary. Retrieved Oct 13, 2026, from https://wordmom.com/dictionary/spark plug
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