1. Electricity. a disruptive discharge around or over the surface of a solid or liquid insulator.
  2. the moment of conflagration or complete incineration caused by superheated air or combustibles.
verb (used without object)
  1. Electricity. to have or experience a flashover.

Origin of flashover

First recorded in 1890–95; orig. noun use of verb phrase flash over
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for flashover


  1. an electric discharge over or around the surface of an insulator
  2. the sudden and rapid spread of fire through the air, caused by the ignition of smoke or fumes from surrounding objects
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012