condemn
To say something is very wrong and must not happen.
To condemn means to express very strong disapproval of something or someone, declaring it completely wrong or unacceptable. When a principal condemns bullying in a school assembly, she's making it absolutely clear that it's deeply wrong and won't be tolerated.
The word carries serious weight. You might criticize a friend's choice of toppings on pizza, but you would condemn someone's decision to cheat or steal. Nations condemn human rights violations. Communities condemn acts of violence. Religious leaders often condemn behaviors they consider morally wrong.
Condemn also has a specific meaning in law and safety: to officially declare something unfit for use. A city might condemn an unsafe building, meaning it must be torn down or can't be entered. A health inspector might condemn food that's spoiled.
Notice that condemning goes beyond disagreement. It's a formal, serious judgment that something is genuinely wrong or dangerous. When you condemn something, you're drawing a clear line and saying it crosses into unacceptable territory.