evanescent
adjective formal uk/ˌiː.vəˈnes.ənt/ us/ˌev.əˈnes.ənt/
短暂的，转瞬即逝的;迅速遗忘的
lasting for only a short time, then disappearing quickly and being forgotten
Synonyms: brief (SHORT IN TIME)ephemeralfleetingfugitive (TEMPORARY) momentarypassing short-livedtransient transitory