isapostolic

from The Century Dictionary.

• Equal to the apostles: an epithet specifically given in the calendar of the Greek Church to bishops of apostolic consecration (for instance, St. Abercius of Hieropolis), holy and eminent women of the apostolic company (as St. Mary Magdalene and St. Thecla), the first preachers of the Christian faith in a country (as St. Nina in Georgia), and persons of royal or princely rank who have promoted the success of Christianity (as St. Constantine and St. Helena).

from the GNU version of the Collaborative International Dictionary of English.

• adjective Having equal, or almost equal, authority with the apostles of their teachings.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective having equivalent, or almost equivalent, authority with the apostles of their teachings.