The Collaborative International Dictionary of English v.0.48:

Dean \Dean\, n. [OE. dene, deene, OF. deien, dien, F. doyen,
   eldest of a corporation, a dean, L. decanus the chief of ten,
   one set over ten persons, e. g., over soldiers or over monks,
   from decem ten. See Ten, and cf. Decemvir.]
   1. A dignitary or presiding officer in certain ecclesiastical
      and lay bodies; esp., an ecclesiastical dignitary,
      subordinate to a bishop.
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   Dean of cathedral church, the chief officer of a chapter;
      he is an ecclesiastical magistrate next in degree to
      bishop, and has immediate charge of the cathedral and its
      estates.

   Dean of peculiars, a dean holding a preferment which has
      some peculiarity relative to spiritual superiors and the
      jurisdiction exercised in it. [Eng.]

   Rural dean, one having, under the bishop, the especial care
      and inspection of the clergy within certain parishes or
      districts of the diocese.
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   2. The collegiate officer in the universities of Oxford and
      Cambridge, England, who, besides other duties, has regard
      to the moral condition of the college. --Shipley.
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   3. The head or presiding officer in the faculty of some
      colleges or universities.
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   4. A registrar or secretary of the faculty in a department of
      a college, as in a medical, or theological, or scientific
      department. [U.S.]
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   5. The chief or senior of a company on occasion of ceremony;
      as, the dean of the diplomatic corps; -- so called by
      courtesy.
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   Cardinal dean, the senior cardinal bishop of the college of
      cardinals at Rome. --Shipley.

   Dean and chapter, the legal corporation and governing body
      of a cathedral. It consists of the dean, who is chief, and
      his canons or prebendaries.

   Dean of arches, the lay judge of the court of arches.

   Dean of faculty, the president of an incorporation or
      barristers; specifically, the president of the
      incorporation of advocates in Edinburgh.

   Dean of guild, a magistrate of Scotch burghs, formerly, and
      still, in some burghs, chosen by the Guildry, whose duty
      is to superintend the erection of new buildings and see
      that they conform to the law.

   Dean of a monastery, Monastic dean, a monastic superior
      over ten monks.

   Dean's stall. See Decanal stall, under Decanal.
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