What is the meaning of Ex_cathedra?

With authority based on one's rank or office.

with the infallible authority of the Pope

with authority, especially one that accepts no objection

ex cathedra (with the infallible authority of the Pope)

ex cathedra (with authority, especially one that accepts no objection)

ex cathedra (with the infallible authority of the Pope)

ex cathedra (with authority, especially one that accepts no objection)

Source: wiktionary.org