Definition of "backfire"

backfire

/bækˈfaɪə(ɹ)/

verb
third-person singular simple present backfires, present participle backfiring, simple past and past participle backfired
1. (of a gun, cannon, Bunsen burner, etc.) To fire in the opposite direction, for example due to an obstruction in the barrel.
2. (of a reciprocating engine) To experience a premature ignition of fuel or an ignition of exhaust gases, making a popping sound.
3. To fail in a manner that brings down further misfortune.
  Quotations
  Obsessed only with cost, 'Sir Humphrey' saw that Transport for London 'got away' with ticket office closures on the Tube with only minor public pushback and miscalculated that it could do the same on the national network. This assumption backfired spectacularly.
  2023 August 9, Nigel Harris, “Comment: Disinterested and dishonest”, in RAIL, number 989, page 3
noun
plural backfires
1. (firefighting) Alternative spelling of back fire
2. A premature explosion in the cylinder of a gas or oil engine during the exhaust or the compression stroke, tending to drive the piston in the wrong direction.
3. An explosion in the exhaust passages of an internal combustion engine.
4. An explosion in other equipment.
  Quotations
  The chief causes of rectifier backfiring in the Glasgow units were overheating or unfavourable anode/cathode temperature differential; it has proved possible to overcome these, although occasional backfires do still occur.
  1962 July, “Failures of multiple-unit electric trains on British Railways”, in Modern Railways, page 53