The Collaborative International Dictionary of English v.0.48:

Synod \Syn"od\ (s[i^]n"[u^]d), n. [L. synodus, Gr. sy`nodos a
   meeting; sy`n with + "odo`s a way; cf. AS. sino[eth],
   seno[eth], F. synode, both from the Latin.]
   1. (Eccl. Hist.) An ecclesiastic council or meeting to
      consult on church matters.
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   Note: Synods are of four kinds: 1. General, or ecumenical,
         which are composed of bishops from different nations;
         -- commonly called general council. 2. National,
         composed of bishops of one nation only. 3. Provincial,
         in which the bishops of only one province meet; --
         called also convocations. 4. Diocesan, a synod in which
         the bishop of the diocese or his representative
         presides. Among Presbyterians, a synod is composed of
         several adjoining presbyteries. The members are the
         ministers and a ruling elder from each parish.
         [1913 Webster]

   2. An assembly or council having civil authority; a
      legislative body.
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            It hath in solemn synods been decreed,
            Both by the Syracusians and ourselves,
            To admit no traffic to our adverse towns. --Shak.
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            Parent of gods and men, propitious Jove!
            And you, bright synod of the powers above. --Dryden.
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   3. (Astron.) A conjunction of two or more of the heavenly
      bodies. [R.] --Milton.
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WordNet (r) 3.0 (2006):

synod
    n 1: a council convened to discuss ecclesiastical business