pre·scrip·tion 
(prĭ-skrĭpshən)
(prĭ-skrĭpshən)n.
1.
a. The action of establishing a rule, law, or direction.
b. Something that is prescribed; a rule, law, or direction: prescriptions for living a moral life.
2.
a. A written order, especially by a physician, for the preparation and administration of a medicine or other treatment.
b. A prescribed medicine or other treatment: Have you used up all of your prescription?
c. An ophthalmologist's or optometrist's written instruction, as for the grinding of corrective lenses.
3. Law The acquisition of an easement or of title to property by use or occupancy that exceeds the time allowed to another to recover it by statutory right.
[Middle English prescripcion, establishment of a claim, from Old French prescription, from Medieval Latin praescrīptiō, praescrīptiōn-, from Latin, introduction, precept, from praescrīptus, past participle of praescrībere, to order; see PRESCRIBE.]