To prescribe means to officially recommend or order something as a solution or treatment. When a doctor prescribes medicine, she's writing an official order that allows you to get that specific medication from a pharmacy. Doctors prescribe antibiotics for infections, glasses for vision problems, or rest for someone who's been working too hard.

The word comes from medicine but works in other contexts too. A teacher might prescribe extra reading practice for a student struggling with comprehension. A coach might prescribe specific drills to fix a problem with your batting stance. The key idea is that someone with expertise is recommending a specific remedy for a specific problem.

Notice how prescribe differs from proscribe, which means to forbid or ban something. If a doctor prescribes an antibiotic, she's ordering you to take it. If she proscribes sugar, she's telling you to avoid it. The similar spelling trips people up, but the meanings point in opposite directions: prescribe says “do this,” while proscribe says “don't do that.”

When you follow a prescription, you're following expert instructions meant to solve your particular problem. That's why prescriptions are specific: they tell you exactly what to take, how much, and when to take it.