1
: an act or instance of burning
Smoke is produced during combustion.
2
: a usually rapid chemical process (such as oxidation) that produces heat and usually light
The carburetor mixes fuel with air for combustion.
also : a slower oxidation (as in the body)
3
: violent agitation : tumult
… periods of great social combustion alternating with quiescence …—Kurt Andersen

Examples of combustion in a Sentence

Combustion may occur at high temperatures. This ratio of air to fuel results in better combustion.
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.
In fact, Dickens was one half of a 10-month long, public debate about whether or not spontaneous human combustion is possible. — Popular Science Team, Popular Science, 4 Nov. 2026 Introduced in 2024, the U9 Xtreme is the kind of EV that can make even an internal-combustion purist change their mind. — Bryan Hood, Robb Report, 4 Nov. 2026 The first is combustion stability, whereby air can extinguish the flame, especially if fuel isn’t mixed well. — Christopher McFadden, Interesting Engineering, 1 Nov. 2026 For several decades, electric cars vied with those powered by steam and internal combustion, and nobody was sure which technology would come out on top. — IEEE Spectrum, 31 Oct. 2026 See All Example Sentences for combustion

Word History

Etymology

Middle English combustioun "burning, calcination," borrowed from Anglo-French & Late Latin; Anglo-French combustion, borrowed from Late Latin combustiōn-, combustiō "burning up (of the dead or by the fires in hell)," from Latin combus-, variant stem of combūrere "to destroy with fire, reduce to ashes" + -tiōn-, tiō, suffix of verbal action — more at combust

First Known Use

15th century, in the meaning defined at sense 1

Time Traveler
The first known use of combustion was in the 15th century

Cite this Entry

“Combustion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/combustion. Accessed 7 Nov. 2026.

Kids Definition

combustion

noun
1
: an act or instance of burning
2
: a chemical process in which substances combine with oxygen

Medical Definition

combustion

noun
: a usually very rapid chemical process (as oxidation) that produces heat and usually light
also : a slower oxidation (as in the body)

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