Authoritative
Au·thor·i·ta·tive
Authoritative
a.
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Having, or proceeding from, due authority; entitled to obedience, credit, or acceptance; determinate; commanding.
The sacred functions of authoritative teaching.
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Having an air of authority; positive; dictatorial; peremptory; as, an authoritative tone.
The mock authoritative manner of the one, and the insipid mirth of the other.