to condemn: to pass a verdict of guilt against someone and declare them deserving of punishment
This word joins the sense of "against" to the ordinary verb for judging (κρίνω), so it never names the neutral weighing of a case but its outcome against the accused: the guilty verdict and the sentence that follows. In the Gospels it is the courtroom word for what the authorities do to Jesus, condemning him to death.
The same act is carried out from very different benches. Human courts hand down the sentence, but so does God, whether on ancient cities, on sin itself, or at the last judgment. Scripture also speaks of a condemnation by contrast: on the last day, people who did respond to God will show up the guilt of those who did not, the way the men of Nineveh who repented will condemn a generation that would not, and the way Noah's obedient faith condemned an unbelieving world.
A quieter use turns the verdict inward. To judge another for what you do yourself is to sentence yourself, and to act against your own conscience is to stand condemned by it. Across all of these, the force is the same: a guilty verdict, not mere disapproval.