‖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, 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.