backflash vs flashback

backflash

noun
  • The hazardous situation where the flame propagates backward down the hose of an oxyfuel welding and cutting system. 

  • Synonym of flashback (“dramatic device”) 

flashback

noun
  • The condition of the flame propagating down the hose of an oxy-fuel welding system. 

  • A dramatic device in which an earlier event is inserted into the normal chronological flow of a narrative. 

  • A query that operates against data from an earlier time, before it was changed. 

  • A vivid mental image of a past trauma or other sensation that the trauma is happening in the present, especially one that recurs. 

  • A similar recurrence of the effects of a hallucinogenic drug. 

verb
  • To undergo a flashback; to experience a vivid mental image from the past. 

How often have the words backflash and flashback occurred in a corpus of books? (source: Google Ngram Viewer )