ephemeron (n.)youdaoicibaDictYouDict[ephemeron 词源字典]
"insect which lives for a very short time in its winged state," 1620s, from Greek (zoon) ephemeron, neuter of adjective ephemeros "living but a day" (see ephemera). Figurative use by 1771.[ephemeron etymology, ephemeron origin, 英语词源]