narthecal--prophetes.ai

narthecal, a. Eccl.
  (nɑːˈθiːkəl)
  [f. narthec-, narthex + -al¹.]
  Of the nature of a narthex.

1866 Ecclesiologist XXVII. 32 The plan shows a western narthecal mass with central vestibule.

Oxford English Dictionary