D defs.my
Entry 1 sense Webster, 1913

Cathedra

· Cath·e·dra · IPA /kəˈθiːdɹə/
01 n. The official chair or throne of a bishop, or of any person in high authority.
  1. 1.
    The official chair or throne of a bishop, or of any person in high authority.
    “The Vatican Council declares that the Pope, is infallible “when he speaks ex cathedra.”” — Addis & Arnold's Cath. Dict.
Phrases & compounds
Ex cathedra — in the exercise of one's office; with authority.