c. 1300, "strange, unfamiliar" (of persons, places), from un- (1) "not" + past participle of know (v.). Compare Old English ungecnawen. In reference to facts, "not discovered or found out," it attested from early 14c. The noun meaning "unknown person" is recorded from 1590s; the unknown "that which is unknown" is from 1650s.
权威例句
1. The best thing to do when entering unknown territory is smile.
踏入未知地带最好的对策就是微笑。
2. It is not unknown for valuable display items to go, ahem, missing.
贵重的展品,呃哼,丢失的话,会众人皆知。
3. The contract was awarded to a previously unknown company.
合同签给了一个之前并不知名的公司。
4. Ignorance of people brings fear, fear of the unknown.
人们的无知会带来恐惧,对未知事物的恐惧。
5. Unknown thieves had forced their way into the apartment.