prescription

noun

the act of prescribing
something prescribed; order; direction; prescript
1. a doctor's written direction for the preparation and use of medicine, the grinding of lenses for eyeglasses, etc.
2. a medicine so prescribed
1. a long-established, authoritative custom
2. a claim based on this
Law
1. the acquirement of the title or right to something through its continued use or possession from time immemorial or over a long period
2. a right or title so acquired

adjective

made according to, or purchasable only with, a doctor's prescription: prescription lenses; a prescription drug

See prescription in American Heritage Dictionary 4