APOSTOLATE more properly denotes the dignity or office of an apostle of Christ; but it is also used, in ancient writers, for the office of a bishop. In this sense we meet with several letters, petitions, requests, &c. directed to bishops under the title of your apostolate, or apostolatus vester. But as the title apostolicus had been appropriated to the pope, so that of apostolate became at length restrained to the sole dignity of the popedom. Every bishop's see was anciently dignified with the title of sedes apostolica, an apostolic see,
Apostoli fee, which is now the peculiar denomination of the fee of Rome.
Apostolici APOSTOLI, in law, denote those letters missive which are demanded in cases of appeal.