Impossible
Not Possible
noun, な adjective
You already know how 可能 means possible. So when you add not it becomes impossible.
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. It will help to know how to read 可能 first as well.
無敵のスーパーマンに、不可能なことは何もなかった。
Nothing was impossible for invincible Superman.
政治に関心が無いのに政治評論家になるのは不可能だ。
It's impossible to be a political observer when you aren't interested in politics.
あのポーカーのトーナメントで、悪い予感はしてたんだけど、捨てるのは不可能な手札を持っていたんだよ。
In the poker tournament, I had a bad feeling, but it wasn’t possible for me to fold my hand.