spark plug

US: (spärk′plug′)

Inflections of 'spark plug' (v): (⇒ conjugate)

sparkplugs

v 3rd person singular

sparkplugging

v pres p

sparkplugged

v past

sparkplugged

v past p

WordReference Random House Learner's Dictionary of American English © 2025

ˈspark ˌplug, n. [countable]

1. Automotive a device that sets on fire the fuel mixture in a cylinder of an engine.
2. Informal Terms a person who leads, inspires, or enlivens others.

WordReference Random House Unabridged Dictionary of American English © 2025

spark′ plug′, 

1. Automotive 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 Terms a person who leads, inspires, or animates a group.
• 1900–05

spark•plug  (spärk′plug′), v.t., -plugged, -plug•ging. [Informal.]

1. Informal Terms to lead, inspire, or animate something or someone.

• verb, verbal use of spark plug

Collins Concise English Dictionary © HarperCollins Publishers::

spark plug, sparkplug / ˈspɑːkˌplʌɡ/ noun

1. a variant of sparking plug