spark plug

noun

1

: a part that fits into the cylinder head of an internal combustion engine and carries two electrodes separated by an air gap across which the current from the ignition system discharges to form the spark for combustion

2

: one that initiates or gives impetus to an undertaking

sparkplug

ˈspärk-ˌpləg 

transitive verb

Examples of spark plug in a Sentence

Recent Examples on the Web

In aviation, iridium-tipped electrodes are used in high-performance spark plugs, providing longer service life and reliable ignition under intense conditions. —Atharva Gosavi, Interesting Engineering, 26 Sep. 2025

The Warriors wind up with Monk, who can prove to be a spark plug for them behind future Hall of Famer Stephen Curry. —Gabe Smallson, MSNBC Newsweek, 20 Sep. 2025

The sixth woman of the year candidate has scored 24, 21, and 18 points in the last three games against the Valkyries and has routinely been the spark plug for Minnesota in stopping the Golden State’s runs. —Nathan Canilao, Mercury News, 17 Sep. 2025

If innovation is the engine of progress, then questions are the spark plugs. —David Henkin, Forbes.com, 9 Sep. 2025

Word History

First Known Use

1903, in the meaning defined at sense 1

Rhymes for spark plug

• debug
• humbug
• prodrug
• unplug
• antidrug
• mealybug
• multidrug
• chug
• doug
• drug
• dug
• hug

Kids Definition

spark plug

noun

1

: a device used in an engine to produce a spark that ignites a fuel mixture

2

: one that begins something or drives something forward