Character
Nature
noun
With time your body will acquire a certain type of character. It shows your true nature as a person.
Note: We almost always use this word in the phrases 得体が知れない/得体の知れない, so check out the context sentences to see what kind of "character" we're talking about.
The reading is a combination of kun'yomi and on'yomi readings. That being said, both readings for both kanji are the readings you learned already, so you should be able to read this.
こんな得体の知れないもの、食べられないよ。
I can’t eat something so strange.
得体の知れない男がさっきからこっちを見ていると思ったら、トーフグのコウイチだった。
I thought a mysterious man was looking at me, but it turned out to be Koichi from Tofugu.
得体の知れない何かが、猛スピードで迫ってくるような感覚に襲われ、冷や汗が止まらなくなりました。
I suddenly felt as if something unidentifiable was coming towards me at furious speeds and I started sweating with fear.