immarcessible (adj.)youdaoicibaDictYouDict[immarcessible 词源字典]
"unfading, imperishable," 1540s, from Late Latin immarcessabilis from assimilated form of in- "not" (see in- (1)) + marcessare "to wither, pine away."[immarcessible etymology, immarcessible origin, 英语词源]