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

There were issues with intake manifold leaks, exhaust manifold cracking, coolant leaks, engine misfires due to corrosion, and water in the spark plug holes. —John Paul, The Providence Journal, 9 Jan. 2026

Boston Celtics spark plug Anfernee Simons, the 7A state player of the year as an Edgewater High senior (2017-18), came off the bench and scored all of his season-high 27 points after halftime in a 115-101 Monday win against Chicago. —Buddy Collings, The Orlando Sentinel, 7 Jan. 2026

Disconnect the spark plug to prevent the mower from accidentally starting during this process. —Karen Brewer Grossman, Southern Living, 5 Jan. 2026

Sea vegetables are also rich in minerals which are the spark plugs of the body. —Mélanie Nauche, Vogue, 20 Dec. 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