obsolete (adj.)youdaoicibaDictYouDict[obsolete 词源字典]
1570s, from Latin obsoletus "grown old, worn out," past participle of obsolescere "fall into disuse," probably from ob "away" (see ob-) + an expanded form of solere "to be used to, be accustomed" (see insolent).[obsolete etymology, obsolete origin, 英语词源]