1. the reliving of a traumatic event after at least some initial adjustment to the trauma appears to have been made. Memories may be triggered by words, sounds, smells, or scenes that are reminiscent of the original trauma (as in a backfiring car triggering a flashback to being in combat). Flashbacks may be associated with posttraumatic stress disorder.

2. the spontaneous recurrence of the perceptual distortions and disorientation to time and place experienced during a previous period of hallucinogen intoxication. Flashbacks may occur months or even years after the last use of the drug and are associated particularly with LSD.