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.
And because there's no exhaust to speak of, the tractor doesn't expose animals or workers to combustion fumes. New Atlas, 17 Sep. 2026 Carbon monoxide released by combustion reduces the amount of oxygen that the blood can carry. Katia Hetter, CNN Money, 16 Sep. 2026 Next came Chicago about a month later, and the internal-combustion convergences take place again on September 19 in New Jersey. Viju Mathew, Robb Report, 16 Sep. 2026 Airbreathing systems such as ramjets and scramjets must also manage airflow and combustion at extreme speeds. Kaif Shaikh, Interesting Engineering, 15 Sep. 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 23 Sep. 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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