In a cathedratic manner; with the authority or manner of pronouncements from a cathedra; in the style of cathedral teaching or governance.
Cathedratical plus the adverbial suffix -ly, creating an adverb from the adjective. This extremely rare form layers Latin suffixes to describe the manner of authoritative episcopal speech.
Words like 'cathedratically' almost never appear in modern English—they're archaeological artifacts showing medieval scholars' obsession with creating labels for every possible nuance.
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