pontificate

pontificate \pon-TIF-i-keyt\, verb:

1. To speak in a pompous or dogmatic manner.
2. To perform the office or duties of a pontiff.
3. To serve as a bishop, especially in a Pontifical Mass.

noun:
1. The office or term of office of a pontiff.

His image is to appear as the guardian of robust morality as opposed to the business world, and he is invited pretty regularly to pontificate on television.
-- Stieg Larsson, The Girl with the Dragon Tattoo

The teacher's vanity and desire to pontificate had, he was vaguely aware, got the better of him.
-- Michael Antony, The Apocalypse Syndrome

Originating from the Latin pontificatus, meaning 'to speak in the manner of a pontiff,' pontificate fell into common usage in 1825.