Source : Webster's Revised Unabridged Dictionary (1913)

Apostolate \A*pos"to*late\, n. [L. apostolatus, fr. apostolus.
   See {Apostle}.]
   1. The dignity, office, or mission, of an apostle;
      apostleship.

            Judas had miscarried and lost his apostolate. --Jer.
                                                  Taylor.

   2. The dignity or office of the pope, as the holder of the
      apostolic see.