Webster's Revised Unabridged Dictionary · 1913

Cathedra

Cathedra , noun

[Latin, from Greek {not transcribed} seat. See Chair.]

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
Collocations (1)
Ex cathedra , in the exercise of one's office; with authority.