The Jargon File (version 4.4.7, 29 Dec 2003):

flame war
 n.

    [common] (var.: flamewar) An acrimonious dispute, especially when conducted
    on a public electronic forum such as Usenet.


The Free On-line Dictionary of Computing (30 December 2018):

flame war

    An acrimonious dispute conducted on a
   public electronic forum such as Usenet.  See flame.

   [Jargon File]

   (1998-05-27)