backfire (Noun) — The backward escape of gases and unburned gunpowder after a gun is fired.
backfire (Noun) — A loud noise made by the explosion of fuel in the manifold or exhaust of an internal combustion engine.
backfire (Noun) — A fire that is set intentionally in order to slow an approaching forest fire or grassfire by clearing a burned area in its path.
backfire (Noun) — A miscalculation that recoils on its maker.
backfire (Verb) — Come back to the originator of an action with an undesired effect. ex. "Your comments may backfire and cause you a lot of trouble"
backfire (Verb) — Emit a loud noise as a result of undergoing a backfire. ex. "My old car backfires all the time"
backfire (Verb) — Set a controlled fire to halt an advancing forest to prairie fire.