The Collaborative International Dictionary of English v.0.48:

Prescription \Pre*scrip"tion\ (pr[-e]*skr[i^]p"sh[u^]n), n. [F.
   prescription, L. praescriptio, an inscription, preface,
   precept, demurrer, prescription (in sense 3), fr.
   praescribere. See Prescribe.]
   [1913 Webster]
   1. The act of prescribing, directing, or dictating;
      direction; precept; also, that which is prescribed.
      [1913 Webster]

   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. Hence: a written order from a
      physician for a medication, which allows a patient to
      legally obtain medication which is required by law to be
      dispensed only on authorization from a physician or other
      qualified medical practitioner.
      [1913 Webster +PJC]

   3. (Law) A prescribing for title; the claim of title to a
      thing by virtue of immemorial use and enjoyment; the right
      or title acquired by possession had during the time and in
      the manner fixed by law. --Bacon.
      [1913 Webster]

            That profound reverence for law and prescription
            which has long been characteristic of Englishmen.
                                                  --Macaulay.
      [1913 Webster]

   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 a right 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.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Usucaption \U`su*cap"tion\ (?; 277), n. [L. usucapere,
   usucaptum, to acquire by long use; usu (ablative of usus use)
   + capere to take: cf. usucapio usucaption.] (Roman Law)
   The acquisition of the title or right to property by the
   uninterrupted possession of it for a certain term prescribed
   by law; -- the same as prescription in common law.
   [1913 Webster]

The Devil's Dictionary (1881-1906):

PRESCRIPTION, n.  A physician's guess at what will best prolong the
situation with least harm to the patient.


Moby Thesaurus II by Grady Ward, 1.0:

205 Moby Thesaurus words for "prescription":
   Procrustean law, act, adverse possession, aid, alodium, alterative,
   analeptic, appurtenance, assistance, authority, balm, balsam, bill,
   birthright, bon ton, boundary, bounds, burgage, bylaw, canon,
   charge, claim, code, colony, command, commission, confinement,
   conformity, conjugal right, consuetude, continence, convention,
   corrective, criterion, cure, custom, de facto, de jure, decree,
   decretum, demand, dependency, derivative title, dictate, dictation,
   direction, directive, discipline, divine right, droit, drug, due,
   edict, enactment, established way, etiquette, faculty, fashion,
   fee fief, fee position, fee simple, fee simple absolute,
   fee simple conditional, fee simple defeasible,
   fee simple determinable, fee tail, feodum, feud, fiefdom, folkway,
   form, formality, formula, formulary, frankalmoign, free socage,
   freehold, gavelkind, general orders, guideline, having title to,
   healing agent, healing quality, help, hold, holding,
   inalienable right, injunction, institute, institution, instruction,
   interest, jus, knight service, law, law of nature, lay fee, lease,
   leasehold, legal claim, legal possession, legislation, lex, limit,
   limitation, mandate, manner, manners, maxim, measure, medicament,
   medication, medicine, moderation, mores, natural right, norm,
   norma, observance, occupancy, occupation, order, order of nature,
   ordinance, ordonnance, original title, owning, possessing,
   possession, power, practice, praxis, precept, preoccupancy,
   preoccupation, preparation, prepossession, prerogative,
   prescribed form, prescript, presumptive right, pretense,
   pretension, principle, proper claim, proper thing, property,
   property right, property rights, proprietary rights, proscription,
   qualification, receipt, recipe, regulation, relief,
   remedial measure, remedy, restorative, restrain, restriction,
   right, ritual, rubric, rule, ruling, seisin, set form, socage,
   social convention, sovereign remedy, specific, specific remedy,
   squatting, standard, standard behavior, standard usage,
   standing custom, standing order, statute, sublease, succor,
   teaching, tenancy, tenantry, tenure, tenure in chivalry,
   time-honored practice, title, tradition, underlease, undertenancy,
   universal law, usage, use, usucapion, vested interest,
   vested right, villein socage, villeinhold, villenage, way,
   what is done, wont, wonting