1. An explosion of prematurely ignited fuel or of unburned exhaust gases in an internal-combustion engine.
2. The backward escape of gases or cartridge fragments when a gun is fired.
3. A fire started in the path of an oncoming fire in order to deprive it of fuel and thereby control or extinguish it.
intr.v. back·fired, back·fir·ing, back·fires
1. To explode in the manner of or make the sound of a backfire.
2. To start or use a backfire in extinguishing or controlling a forest fire.
3. To produce an unexpected, undesired result.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 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.