Biblical evil is the opposite of good. Example…
Jeremiah 18
7 At what instant I shall speak concerning a nation, and concerning a kingdom, to pluck up, and to pull down, and to destroy it;
8 If that nation, against whom I have pronounced, turn from their evil, I will repent of the evil that I thought to do unto them.
9 And at what instant I shall speak concerning a nation, and concerning a kingdom, to build and to plant it;
10 If it do evil in my sight, that it obey not my voice, then I will repent of the good, wherewith I said I would benefit them.