The Collaborative International Dictionary of English v.0.48:

Ordinance \Or"di*nance\, n. [OE. ordenance, OF. ordenance, F.
   ordonnance. See Ordain, and cf. Ordnance, Ordonnance.]
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   1. Orderly arrangement; preparation; provision. [Obs.]
      --Spenser.
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            They had made their ordinance
            Of victual, and of other purveyance.  --Chaucer.
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   2. A rule established by authority; a permanent rule of
      action; a statute, law, regulation, rescript, or accepted
      usage; an edict or decree; esp., a local law enacted by a
      municipal government; as, a municipal ordinance.
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            Thou wilt die by God's just ordinance. --Shak.
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            By custom and the ordinance of times. --Shak.
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            Walking in all the commandments and ordinances of
            the Lord blameless.                   --Luke i. 6.
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   Note: Acts of Parliament are sometimes called ordinances;
         also, certain colonial laws and certain acts of
         Congress under Confederation; as, the ordinance of 1787
         for the government of the territory of the United
         States northwest of the Ohio River; the colonial
         ordinance of 1641, or 1647. This word is often used in
         Scripture in the sense of a law or statute of sovereign
         power. --Ex. xv. 25. --Num. x. 8. --Ezra iii. 10. Its
         most frequent application now in the United States is
         to laws and regulations of municipal corporations.
         --Wharton (Law Dict.).
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   3. (Eccl.) An established rite or ceremony.
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   4. Rank; order; station. [Obs.] --Shak.
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   5. [See Ordnance.] Ordnance; cannon. [Obs.] --Shak.
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WordNet (r) 3.0 (2006):

ordinance
    n 1: an authoritative rule [syn: regulation, ordinance]
    2: a statute enacted by a city government
    3: the act of ordaining; the act of conferring (or receiving)
       holy orders; "the rabbi's family was present for his
       ordination" [syn: ordination, ordinance]

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "ordinance":
   act, appointment, bill, brevet, bull, bylaw, canon, ceremonial,
   ceremony, code, commandment, convention, declaration, decree,
   decree-law, decreement, decretal, decretum, dictate, dictation,
   dictum, diktat, duty, edict, edictum, enactment, fiat, form,
   form of worship, formality, formula, formulary, function,
   general principle, golden rule, guideline, guiding principle,
   holy rite, imperative, institution, ipse dixit, jus, law,
   legislation, lex, liturgy, maxim, measure, mitzvah,
   mode of worship, moral, mystery, norm, observance, office,
   order of worship, ordonnance, practice, precept, prescribed form,
   prescript, prescription, principium, principle, proclamation,
   pronouncement, pronunciamento, regulation, rescript, rite, ritual,
   ritual observance, rituality, rubric, rule, ruling, sacrament,
   sacramental, senatus consult, senatus consultum, service,
   settled principle, solemnity, standard, standing order, statute,
   tenet, ukase, working principle, working rule



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

ORDINANCE, legislation. A law, a statute, a decree.
     2. This word is more usually applied to the laws of a corporation, than
to the acts of the legislature; as the ordinances of the city of
Philadelphia. The following account of the difference between a statute and
an ordinance is extracted from Bac. Ab. Statute, A. "Where the proceeding
consisted only of a petition from parliament, and an answer from the king,
these were entered on the parliament roll; and if the matter was of a public
nature, the whole was then styled an ordinance; if, however, the petition
and answer were not only of a public, but a novel nature, they were then
formed into an act by the king, with the aid of his council and judges, and
entered on the statute roll." See Harg. & But. Co. Litt. l59 b, notis; 3
Reeves, Hist. Eng. Law, 146.
     3. According to Lord Coke, the difference between a statute and an
ordinance is, that the latter has not had the assent of the king, lords, and
commons, but is made merely by two of those powers. 4 Inst. 25. See Barr. on
Stat. 41, note (x).