1. The process of burning.
2. A heat-producing chemical reaction in which a fuel combines with oxygen or with some other substance that behaves chemically like oxygen.
3. Violent anger or agitation: Combustion within the populace slowly built up to the point of revolution.
[Middle English, from Late Latin combustiō, combustiōn-, from Latin combustus, past participle of combūrere, to burn up, blend of com-, intensive pref.; see COM- and ambūrere, to burn around (amb-, ambi-, ambi- + ūrere, to burn).]
com·bustive (-tĭv) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.