Cathedra \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.

Source: Webster's Revised Unabridged Dictionary (1913)