Collins Chinese Dictionary Plus (3rd edition), 2011:
unknown [ʌnˈnəun]
I adj
1
[+ fact, number] 未知的 wèizhī de
2
[+ writer, artist] 名不见(見)经(經)传(傳)的 míng bù jiàn jīngzhuàn de
3
(=unidentified)
[+ person] 陌生的 mòshēng de
[+ person] 陌生的 mòshēng de
II n
1
[c]
(=person) 无(無)名小卒 wúmíng xiǎozú
2
[s]
(=thing) 未知事物 wèizhī shìwù
- he was unknown to me
我不认(認)识(識)他 wǒ bù rènshi tā - unknown to me, he…
不为(為)我所知，他… bù wéi wǒ suǒ zhī，tā… - it is not unknown for travellers to forget their passports
旅客忘带(帶)护(護)照的事并(並)不少见(見) lǚkè wàng dài hùzhào de shì bìng bù shǎojiàn - an unknown quantity
一个(個)未知数(數) yī gè wèizhīshù - fear of the unknown
对(對)未知事物的恐惧(懼) duì wèizhī shìwù de kǒngjù
在这些条目还发现'unknown'：
在英文解释里：
and God knows what
- anonymity
- blind date
- community spread
- exploration
- float around
- for some reason
- idiopathic
- Jane Doe
- John Doe
- obscurity
- rando
- stranger rape
- terra incognita
- thingy
- umpteenth
- unattributed
- unexplained
- unsub
- who knows
中文：