backflash

From back +‎ flash.

backflash (plural backflashes)

1. The hazardous situation where the flame propagates backward down the hose of an oxyfuel welding and cutting system.
2. Synonym of flashback (“dramatic device”)
   • 2004, David Mitchell, Cloud Atlas, London: Hodder and Stoughton, →ISBN:

     As an experienced editor I disapprove of backflashes, foreshadowings and tricksy devices […]

• flash back, flashback, half-backs, halfbacks