unicornyoudaoicibaDictYouDict[unicorn 词源字典]
unicorn: [13] Legends of a one-horned beast abounded in ancient times, perhaps inspired by the rhinoceros, or a sideways view of an antelope. When the early Greek translators of the Hebrew Bible came across the word re’em, which seems to have denoted a sort of wild ox, they rendered it monókerōs (literally ‘onehorn’), perhaps identifying it with the rhinoceros. The Vulgate turned this into Latin as unicornis, a noun use of an already existent Latin adjective meaning ‘one-horned’, formed from ūnus ‘one’ and cornū ‘horn’ (a relative of English horn).
=> horn[unicorn etymology, unicorn origin, 英语词源]
unicorn (n.)youdaoicibaDictYouDict
early 13c., from Old French unicorne, from Late Latin unicornus (Vulgate), from noun use of Latin unicornis (adj.) "having one horn," from uni- "one" (see uni-) + cornus "horn," from PIE *ker- (1) "horn; head, uppermost part of the body" (see horn (n.)).

The Late Latin word translates Greek monoceros, itself rendering Hebrew re'em (Deut. xxxiii.17 and elsewhere), which probably was a kind of wild ox. According to Pliny, a creature with a horse's body, deer's head, elephant's feet, lion's tail, and one black horn two cubits long projecting from its forehead. Compare German Einhorn, Welsh ungorn, Breton uncorn, Old Church Slavonic ino-rogu.