\Cath"e*dra\, n. [L., fr. Gr. ? seat. See {Chair}.]
The official chair or throne of a bishop, or of any person in
high authority.
{Ex cathedra} [L., from the chair], in the exercise of one's
   office; with authority.
         The Vatican Council declares that the Pope, is
         infallible ``when he speaks ex cathedra.'' --Addis &
                                               Arnold's Cath.
                                               Dict.