To proscribe something means to officially forbid or ban it. When a school proscribes cellphone use during class, students aren't allowed to have their phones out. When a doctor proscribes a certain food for a patient with allergies, that patient must avoid eating it.

The word carries a sense of authority and formality. Your parents might forbid you from staying up past bedtime, but a government proscribes certain activities by making them illegal. In some times and places, authorities have proscribed entire books, declaring them too dangerous to read or own.

Be careful not to confuse proscribe with prescribe, which means something different: to recommend or order something as beneficial. A doctor prescribes medicine (tells you to take it) but proscribes activities that might harm your recovery (tells you not to do them). The difference matters: prescribed medication is what you should take, while proscribed medication is what you must avoid.

When something is proscribed, there are usually consequences for ignoring the ban. A proscribed organization might face legal penalties. Proscribed behavior in a courtroom could lead to removal from the courtroom.