domainyoudaoicibaDictYouDict[domain 词源字典]
domain: [17] Etymologically, domain means ‘land belonging to a lord’, but its resemblance to such words as dominate and dominion is somewhat adventitious. Until the 17th century it was essentially the same word as demesne: demaine or demeine ‘lord’s estate’ was the Old French equivalent of (and indeed source of) English demesne. It came ultimately from Latin dominicus ‘of a lord’, but its etymological connection with Latin dominus ‘lord’ had become somewhat obscured over the centuries.

But then, around 1600, by association with Latin dominium (source of English dominion), French demaine became altered to domaine, which English borrowed as domain.
=> dame, demesne, dominate, dominion[domain etymology, domain origin, 英语词源]
domain (n.)youdaoicibaDictYouDict
early 15c., in Scottish, from Middle French domaine "domain, estate," from Old French demaine "lord's estate," from Latin dominium "property, dominion," from dominus "lord, master, owner," from domus "house" (see domestic). Form influenced in Old French by Medieval Latin domanium "domain, estate." Internet domain name attested by 1985.