Unknown, Unclear, Uncertain, Unsure
noun, な adjective
Something that is not bright is cloudy and fuzzy. What do you think when you look into the fuzzy clouds? It is the unknown, the unclear, the uncertain.
ふめい
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
このホテルは、オーナーが不明です。
The owner of this hotel is unknown.
生まれた日は不明です。
The day of birth is unknown.
私の兄は今どこにいるか不明なんです。
It's uncertain where my brother is now.