allocution

allocution \al-uh-KYOO-shuhn\, noun:

1. A formal speech, especially one of an incontrovertible or hortatory nature.
2. A pronouncement delivered by the pope to a secret consistory, especially on a matter of policy or of general importance.

The little crowd, with some ironical cheers and hootings, nevertheless felt the force of Madame Fribsby's vigorous allocution, and retreated before her…
-- William Makepeace Thackeray, The History of Pendennis

Towards midday, the abbé Pirard took leave of his pupils, not without first delivering a severe allocution.
-- Stendhal, The Red and the Black

Allocution stems from the Latin root alloquī which meant to "to speak, address." The suffix -ion forms nouns from stems, as in the words communion and opinion.