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]