The quality or state of being authoritative; having recognized power, expertise, or the ability to make final decisions.
From 'authoritative' plus '-ness' (Old English suffix forming abstract nouns). The noun form allows us to discuss the abstract quality of having authority and expertise.
What makes something 'authoritative' is interesting—it's not just about being right, but about social recognition of power and expertise, which is why dictionaries work hard to show their authoritativeness through their presentation and citations.
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