flashback (n.)youdaoicibaDictYouDict[flashback 词源字典]
also flash-back, 1903 in reference to fires in engines or furnaces, from verbal phrase (1902), from flash (v.) + back (adv.). Movie plot device sense is from 1916. The hallucinogenic drug sense is attested in psychological literature from 1970, which means probably hippies were using it a few years before.[flashback etymology, flashback origin, 英语词源]