back fire

Meaning

Noun

• A small, controlled fire set in the path of a larger uncontrolled fire, in order to limit the spread of the large fire by removing its fuel.
• An explosion produced either by a running internal combustion engine that occurs in the air intake or exhaust system rather than inside the combustion chamber or unburned fuel or hydrocarbons ignited somewhere in the exhaust system.

Origin

• back + fire