The Collaborative International Dictionary of English v.0.48:

Edict \E"dict\, n. [L. edictum, fr. edicere, edictum, to
   declare, proclaim; e out + dicere to say: cf. F. ['e]dit. See
   Diction.]
   A public command or ordinance by the sovereign power; the
   proclamation of a law made by an absolute authority, as if by
   the very act of announcement; a decree; as, the edicts of the
   Roman emperors; the edicts of the French monarch.
   [1913 Webster]

         It stands as an edict in destiny.        --Shak.
   [1913 Webster]

   Edict of Nantes (French Hist.), an edict issued by Henry
      IV. (A. D. 1598), giving toleration to Protestants. Its
      revocation by Louis XIV. (A. D. 1685) was followed by
      terrible persecutions and the expatriation of thousands of
      French Protestants.

   Syn: Decree; proclamation; law; ordinance; statute; rule;
        order; manifesti; command. See Law.
        [1913 Webster]

WordNet (r) 3.0 (2006):

edict
    n 1: a formal or authoritative proclamation
    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]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "edict":
   act, announcement, annunciation, appointment, bill, brevet, bull,
   bulletin board, bylaw, canon, circular, communique, declaration,
   decree, decree-law, decreement, decretal, decretum, dictate,
   dictation, dictum, diktat, directive, edictum, enactment,
   encyclical, enunciation, fiat, form, formality, formula, formulary,
   institution, instrument, ipse dixit, jus, law, legislation, lex,
   manifesto, measure, notice, notification, order, ordinance,
   ordonnance, position paper, precept, prescript, prescription,
   proclamation, program, programma, pronouncement, pronunciamento,
   public notice, regulation, report, rescript, rubric, rule, ruling,
   senatus consult, senatus consultum, standing order, statement,
   statute, ukase, white book, white paper



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

EDICT. A law ordained by the sovereign, by which he forbids or commands
something it extends either to the whole country, or only to some particular
provinces.
     2. Edicts are somewhat similar to public proclamations. Their
difference consists in this, that the former have authority and form of law
in themselves, whereas the latter are at most, declarations of a law, before
enacted by congress, or the legislature.
     3. Among the Romans this word sometimes signified, a citation to appear
before a judge. The edict of the emperors, also called constitutiones
principum, were new laws which they made of their own motion, either to
decide cases which they had foreseen, or to abolish or change some ancient
laws. They were different from their rescripts or decrees. These edicts were
the sources which contributed to the formation of the Gregorian,
Hermogenian, Theodosian, and Justinian Codes. Vide Dig. 1, 4, 1, 1; Inst. 1,
2, 7; Code, 1, 1 Nov. 139.