The Collaborative International Dictionary of English v.0.48:

Prescript \Pre"script\, a. [L. praescriptus, p. p. of
   praescribere: cf. F. prescrit. See Prescribe.]
   Directed; prescribed. " A prescript from of words." --Jer.
   Taylor.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prescript \Pre"script\, n. [L. praescriptum: cf. OF. prescript.]
   [1913 Webster]
   1. Direction; precept; model prescribed. --Milton.
      [1913 Webster]

   2. A medical prescription. [Obs.] --Bp. Fell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

prescript
    n 1: prescribed guide for conduct or action [syn: rule,
         prescript]

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "prescript":
   act, adage, ana, analects, aphorism, apothegm, axiom, bill, bylaw,
   byword, canon, catchword, charge, collected sayings, command,
   commission, current saying, decree, decretum, dictate, dictation,
   dictum, direction, directive, distich, edict, enactment, epigram,
   expression, form, formality, formula, formulary, general orders,
   gnome, golden saying, injunction, institute, institution,
   instruction, jus, law, legislation, lex, maxim, measure, moral,
   mot, motto, oracle, order, ordinance, ordonnance, phrase,
   pithy saying, precept, prescription, proverb, proverbial saying,
   proverbs, regulation, rubric, rule, ruling, saw, saying, sentence,
   sententious expression, sloka, standing order, statute,
   stock saying, sutra, teaching, text, verse, wisdom,
   wisdom literature, wise saying, witticism, word, words of wisdom