The Collaborative International Dictionary of English v.0.48:

Charter \Char"ter\, n. [OF. chartre, F. chartre, charte, fr. L.
   chartula a little paper, dim. of charta. See Chart,
   Card.]
   1. A written evidence in due form of things done or granted,
      contracts made, etc., between man and man; a deed, or
      conveyance. [Archaic]
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   2. An instrument in writing, from the sovereign power of a
      state or country, executed in due form, bestowing rights,
      franchises, or privileges.
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            The king [John, a.d. 1215], with a facility somewhat
            suspicious, signed and sealed the charter which was
            required of him. This famous deed, commonly called
            the "Great Charter," either granted or secured very
            important liberties and privileges to every order of
            men in the kingdom.                   --Hume.
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   3. An act of a legislative body creating a municipal or other
      corporation and defining its powers and privileges. Also,
      an instrument in writing from the constituted authorities
      of an order or society (as the Freemasons), creating a
      lodge and defining its powers.
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   4. A special privilege, immunity, or exemption.
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            My mother,
            Who has a charter to extol her blood,
            When she does praise me, grieves me.  --Shak.
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   5. (Com.) The letting or hiring a vessel by special contract,
      or the contract or instrument whereby a vessel is hired or
      let; as, a ship is offered for sale or charter. See
      Charter party, below.
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   Charter land (O. Eng. Law), land held by charter, or in
      socage; bookland.

   Charter member, one of the original members of a society or
      corporation, esp. one named in a charter, or taking part
      in the first proceedings under it.

   Charter party [F. chartre partie, or charte partie, a
      divided charter; from the practice of cutting the
      instrument of contract in two, and giving one part to each
      of the contractors] (Com.), a mercantile lease of a
      vessel; a specific contract by which the owners of a
      vessel let the entire vessel, or some principal part of
      the vessel, to another person, to be used by the latter in
      transportation for his own account, either under their
      charge or his.

   People's Charter (Eng. Hist.), the document which embodied
      the demands made by the Chartists, so called, upon the
      English government in 1838.
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WordNet (r) 3.0 (2006):

charter member
    n 1: one of the original members when an organization was
         founded