a. A literary or cinematic device in which an earlier event is inserted into the normal chronological order of a narrative.

b. The episode or scene depicted by means of this device.

a. Psychiatry A recurring, intensely vivid mental image of a past traumatic experience: soldiers who had flashbacks of the war.

b. An unexpected recurrence of the effects of a hallucinogenic drug long after its original use.

c. A vivid memory that arises spontaneously or is provoked by an experience.

d. An experience that has characteristics of an earlier experience.