Prescribe - proscribe

These are an unfortunate pair of words. Both are verbs; they have associated nouns ending in '-iption', prescription and proscription. There are also related adjectives prescriptive and proscriptive. Although they sound virtually identical, except in the mouths of very careful speakers speaking carefully, and although there is only one letter different when they are written. their meanings are opposite.

• prescribe means 'to lay down' (a rule); 'to order' (as a recipe for the good of the receiver), or 'to advise'. Doctors commonly prescribe medicines for their patients (the piece of paper on which their instructions are written is a prescription). An academic tutor might prescribe a particular course of reading for a student; there may be a prescribed format in which the latter should write an assignment.
• proscribe on the other hand means 'to ban', or 'to order no contact with'. At some periods in the UK, criminals could be punished by being proscribed, that is they were 'banned' - in effect, they became outlaws. They usually had to go into exile. One can also proscribe such things as particular habits, religions and practices.

Students of linguistics should also be careful to distinguish between prescriptive and descriptive.