flash ‧ back /ˈflæʃbæk/ BrE AmE noun
1 . [uncountable and countable] a scene in a film, play, book etc that shows something that happened before that point in the story:
The events of the hero’s childhood are shown as a series of flashbacks.
2 . [countable] a sudden very clear memory of something that happened to you in the past:
Eaton still has flashbacks of the crash.
3 . [countable] an occasion when someone has the same bad feeling that they had when they took an illegal drug in the past:
Many users of this drug experience flashbacks.
4 . [countable] technical a burning gas or liquid that moves back into a tube or container