The Collaborative International Dictionary of English v.0.48:

Rescript \Re"script\ (r?"skr?pt), n. [L. rescriptum: cf. F.
   rescrit, formerly also spelt rescript. See Rescribe,v. t.]
   [1913 Webster]
   1. (Rom.Antiq.) The answer of an emperor when
      formallyconsulted by particular persons on some difficult
      question; hence, an edict or decree.
      [1913 Webster]

            In their rescripts and other ordinances, the Roman
            emperors spoke in the plural number.  --Hare.
      [1913 Webster]

   2. (R.C.Ch.) The official written answer of the pope upon a
      question of canon law, or morals.
      [1913 Webster]

   3. A counterpart. --Bouvier.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rescript
    n 1: a reply by a Pope to an inquiry concerning a point of law
         or morality
    2: a legally binding command or decision entered on the court
       record (as if issued by a court or judge); "a friend in New
       Mexico said that the order caused no trouble out there" [syn:
       decree, edict, fiat, order, rescript]
    3: the act of rewriting something [syn: revision, revisal,
       revise, rescript]
    4: something that has been written again; "the rewrite was much
       better" [syn: rewrite, revision, rescript]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "rescript":
   acknowledgment, amendment, answer, answering, antiphon,
   appointment, back answer, back talk, backchat, billet, brevet,
   bull, business letter, chit, comeback, communication, correction,
   declaration, decree, decree-law, decreement, decretal, decretum,
   dictum, diktat, dispatch, echo, edict, edictum, editing,
   emendation, epistle, evasive reply, favor, fiat, ipse dixit, law,
   letter, line, message, missive, note, ordinance, ordonnance,
   proclamation, pronouncement, pronunciamento, reaction, ready reply,
   receipt, recension, rectification, redaction, redraft, rejoinder,
   repartee, replication, reply, repost, rescription, respondence,
   response, responsion, responsory, retort, return, revampment,
   reverberation, review, revisal, revise, revised edition, revision,
   rewrite, rewriting, riposte, rule, ruling, senatus consult,
   senatus consultum, short answer, snappy comeback, ukase,
   witty reply, witty retort, yes-and-no answer



Bouvier's Law Dictionary, Revised 6th Ed (1856):

RESCRIPT, conv. A counterpart.
     2. In the canon law, by rescripts are understood apostolical letters,
which emanate from the pope, under whatever form they may be. The answers of
the pope in writing are so called. Diet. Dr. Can. h.v. Vide Chirograph;
Counterpart; Part.