The Collaborative International Dictionary of English v.0.48:

Vicar \Vic"ar\ (v[i^]k"[~e]r), n. [OE. vicar, viker, vicair, F.
   vicaire, fr. L. vicarius. See Vicarious.]
   1. One deputed or authorized to perform the functions of
      another; a substitute in office; a deputy. [R.]
      [1913 Webster]

   2. (Eng. Eccl. Law) The incumbent of an appropriated
      benefice.
      [1913 Webster]

   Note: The distinction between a parson [or rector] and vicar
         is this: The parson has, for the most part, the whole
         right to the ecclesiastical dues in his parish; but a
         vicar has generally an appropriator over him, entitled
         to the best part of the profits, to whom he is in fact
         perpetual curate with a standing salary. --Burrill.
         [1913 Webster]

   Apostolic vicar, or Vicar apostolic. (R. C. Ch.)
      (a) A bishop to whom the Roman pontiff delegates a portion
          of his jurisdiction.
      (b) Any ecclesiastic acting under a papal brief,
          commissioned to exercise episcopal authority.
      (c) A titular bishop in a country where there is no
          episcopal see, or where the succession has been
          interrupted.

   Vicar forane. [Cf. LL. foraneus situated outside of the
      episcopal city, rural. See Vicar, and Foreign.] (R. C.
      Ch.) A dignitary or parish priest appointed by a bishop to
      exercise a limited jurisdiction in a particular town or
      district of a diocese. --Addis & Arnold.

   Vicar-general.
      (a) (Ch. of Eng.) The deputy of the Archbishop of
          Canterbury or York, in whose court the bishops of the
          province are confirmed. --Encyc. Brit.
      (b) (R. C. Ch.) An assistant to a bishop in the discharge
          of his official functions.

   Vicar of Jesus Christ (R. C. Ch.), the pope as representing
      Christ on earth.
      [1913 Webster]
      [1913 Webster]

WordNet (r) 3.0 (2006):

vicar-general
    n 1: (Roman Catholic Church) an administrative deputy who
         assists a bishop