spontaneous combustion

American  

noun

1. the ignition of a substance or body from the rapid oxidation of its own constituents without heat from any external source.

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spontaneous combustion British  

noun

1. the ignition of a substance or body as a result of internal oxidation processes, without the application of an external source of heat, occurring in finely powdered ores, coal, straw, etc

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spontaneous combustion Scientific  

1. The bursting into flame of a mass of material as a result of chemical reactions within the substance, without the addition of heat from an external source. Oily rags and damp hay, for example, are subject to spontaneous combustion.

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spontaneous combustion Cultural  

1. A process by which a collection of materials (such as oily rags) catches fire without the application of heat from outside. The oxidation of substances in the materials starts the fire.

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Etymology

Origin of spontaneous combustion

First recorded in 1800–10

Example Sentences

They were also located in a layer that lacked guano deposits, ruling out spontaneous combustion as an explanation.

From Science Daily • Jun. 24, 2026

"So it started with that flame. It was like spontaneous combustion."

From BBC • Mar. 17, 2026

But Vaillant also characterizes the wildfire as a “regional apocalypse” and imminent flashover—the point of spontaneous combustion in an enclosed space—as “a malevolent entity from another dimension breaking through to this one.”

From Scientific American • Jun. 18, 2023

This can happen for reasons ranging from spontaneous combustion to human irresponsibility.

From Salon • Mar. 4, 2023

They’d found it worked on Nico better than nectar, helping to cleanse the fatigue and darkness from his system with less danger of spontaneous combustion.

From "Blood of Olympus" by Rick Riordan