ex ca·the·dra /ˌɛkskəˈθidrə/
Cath·e·dra n. 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.
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