Definition of: backfire

(bak′fīr′) noun
1. A fire built to check an advancing forest or prairie fire by creating a barren area in its path.
2. Premature explosion in the cylinder of an internal-combustion engine.
3. An explosion in the back part of a gun.
—v.i. ·fired, ·fir·ing
1. To set or use a backfire.
2. To explode in a backfire.
3. To have consequences contrary to those desired: The plan to raise revenue by increasing the sales tax backfired when sales dropped off.