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]