Source : Webster's Revised Unabridged Dictionary (1913)

Prescription \Pre*scrip"tion\, n. [F. prescription, L.
   praescriptio, an inscription, preface, precept, demurrer,
   prescription (in sense 3), fr. praescribere. See
   {Prescribe}.]
   1. The act of prescribing, directing, or dictating;
      direction; precept; also, that which is prescribed.

   2. (Med.) A direction of a remedy or of remedies for a
      disease, and the manner of using them; a medical recipe;
      also, a prescribed remedy.

   3. (Law) A prescribing for title; the claim of title to a
      thing by virtue immemorial use and enjoyment; the right or
      title acquired by possession had during the time and in
      the manner fixed by law. --Bacon.

            That profound reverence for law and prescription
            which has long been characteristic of Englishmen.
                                                  --Macaulay.

   Note: Prescription differs from custom, which is a local
         usage, while prescription is personal, annexed to the
         person only. Prescription only extends to incorporeal
         rights, such as aright of way, or of common. What the
         law gives of common rights is not the subject of
         prescription. Blackstone. Cruise. Kent. In Scotch law,
         prescription is employed in the sense in which
         limitation is used in England and America, namely, to
         express that operation of the lapse of time by which
         obligations are extinguished or title protected. Sir T.
         Craig. Erskine.

Source : WordNet®

prescription
     n 1: directions prescribed beforehand; the action of prescribing
          authoritative rules or directions; "I tried to follow
          her prescription for success"
     2: a drug that is available only with written instructions from
        a doctor or dentist to a pharmacist; "he told the doctor
        that he had been taking his prescription regularly" [syn:
        {prescription drug}, {prescription medicine}, {ethical
        drug}] [ant: {over-the-counter drug}, {over-the-counter
        drug}]
     3: written instructions for an optician on the lenses for a
        given person
     4: written instructions from a physician or dentist to a
        druggist concerning the form and dosage of a drug to be
        issued to a given patient

prescription
     adj : available only with a doctor's written prescription; "a
           prescription drug" [syn: {prescription(a)}] [ant: {nonprescription(a)}]