flashover \ˈ ̷ ̷ˌ ̷ ̷ ̷ ̷\noun (-s) Usage:often attributive Etymology:flash (I) + over 1.: an electrical discharge or arc through the air to the ground from a high potential source or between two conducting portions of a machine or structure 2.: the sudden spread of flame over an area when it becomes heated to the flash point