Ignition of a substance, such as oily rags or hay, caused by a localized heat-increasing reaction between the oxidant and the fuel and not involving addition of heat from an outside source.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "spontaneous combustion" in a sentence
"Mr. Barnabas had come striding from his house in the Crescent, had turned the corner, and was apparently marching on to the little tobacconist’s at the end of the street, where it was his custom to stop and pick up a copy of the Times and the Standard, when unfortunately he stepped into the fourth dimension or was the victim of spontaneous combustion or some sort of accident to an atom."
""I think it must have been spontaneous combustion in the paint-locker."