1
a
: the device that is used to ignite the fuel mixture in a gasoline engine
put the key in the ignition
b
: the process or means (such as an electric spark) of igniting a fuel mixture
2
: the act or action of igniting: such as
a
: the starting of a fire
b
: the heating of a plasma to a temperature high enough to sustain nuclear fusion

Examples of ignition in a Sentence

There's a problem with the car's ignition.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Whatever the ignition source, Pohl says people tend to start wildfires in or near populated areas. Kirk Siegler, NPR, 27 Aug. 2026 Next, ground crews, including the Navajo hotshots, will start hand and aerial ignitions, the department said. Joan Meiners, AZCentral.com, 27 Aug. 2026 Officials said the fire was human-caused but the source of the ignition remains under investigation. Christopher Cann, USA Today, 25 Aug. 2026 The clip shows the moment of ignition of one of the spacecraft's six Raptor 3 engines, which burns for approximately 15 seconds. Josh Dinner, Space.com, 21 Aug. 2026 See All Example Sentences for ignition

Word History

First Known Use

1612, in the meaning defined at sense 2

Time Traveler
The first known use of ignition was in 1612

Browse Nearby Words

Cite this Entry

“Ignition.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ignition. Accessed 1 Sep. 2026.

Kids Definition

ignition

noun
1
: the act of igniting
2
: the process or means (as an electric spark) of igniting a fuel mixture
also : an electrical device for operating an ignition system (as in an automobile)
put the key in the ignition

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