The Collaborative International Dictionary of English v.0.48:

Ban \Ban\ (b[a^]n), n. [AS. bann command, edict; akin to D. ban,
   Icel. bann, Dan. band, OHG. ban, G. bann, a public
   proclamation, as of interdiction or excommunication, Gr.
   fa`nai to say, L. fari to speak, Skr. bhan to speak; cf. F.
   ban, LL. bannum, of G. origin. [root]86. Cf. Abandon,
   Fame.]
   1. A public proclamation or edict; a public order or notice,
      mandatory or prohibitory; a summons by public
      proclamation.
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   2. (Feudal & Mil.) A calling together of the king's (esp. the
      French king's) vassals for military service; also, the
      body of vassals thus assembled or summoned. In present
      usage, in France and Prussia, the most effective part of
      the population liable to military duty and not in the
      standing army.
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   3. pl. Notice of a proposed marriage, proclaimed in church.
      See Banns (the common spelling in this sense).
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   4. An interdiction, prohibition, or proscription. "Under ban
      to touch." --Milton.
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   5. A curse or anathema. "Hecate's ban." --Shak.
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   6. A pecuniary mulct or penalty laid upon a delinquent for
      offending against a ban; as, a mulct paid to a bishop by
      one guilty of sacrilege or other crimes.
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   Ban of the empire (German Hist.), an imperial interdict by
      which political rights and privileges, as those of a
      prince, city, or district, were taken away.
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