The word "prescribe" means to give direction or an order for something to be done. The antonyms for "prescribe" would be "prohibit", "forbid", "disallow", "ban", "proscribe", "discourage", "dissuade", or "oppose". These antonyms signify a refusal or denial of the direction that the word "prescribe" implies. For example, a doctor may prescribe a medication to a patient to help with their illness, but a nurse may discourage the use of that medication due to its adverse side effects. In essence, antonyms for "prescribe" indicate negation or denial of what is expected or recommended.