Definitions for "Flashover"
A vehicle with crew being engulfed by fire for a short period of time
(noun) the sudden spread of flame over an area when it becomes heated to the flash point (Date: 1892) (Merriam-Webster's Unabridged at
A temperature at which a fire hazard is in danger of unrestrained fire growth and complete destruction. The exact temperature depends on different types of hazards and their inherent characteristics (such as age, condition, materials of construction, proximity to other structures and other factors).
an unintended electric discharge (as over or around an insulator)
A disruptive discharge around or over the surface of an insulator.
Flashing due to high current flowing between two points of different potential. Usually due to insulation breakdown resulting from arcing or lightning.