bù míng
not clear
unknown
to fail to understand
bù míng fēi xíng wù
unidentified flying object (UFO)
xià luò bù míng
unaccounted
unknown whereabouts
lái lù bù míng
unidentified origin
no-one knows where it comes from
of dubious background
bù míng shì lǐ
not understanding things (idiom); devoid of sense
bù míng jiù lǐ
not to understand the situation
unaware of the ins and outs
bù míng jué lì
although I don't understand it, it seems pretty awesome (Internet slang)