authoritative

adj. official; reliable; assertive, commanding

Being authoritative can mean several things.
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Adjective
1. having authority or ascendancy or influence; "an important official"; "the captain's authoritative manner"
(synonym) important
(similar) influential
2. of recognized authority or excellence; "the definitive work on Greece"; "classical methods of navigation"
(synonym) classical, definitive
(similar) standard
3. sanctioned by established authority; "an authoritative communique"; "the authorized biography"
(synonym) authorized, authorised
(similar) official

(a.)
Having, or proceeding from, due authority; entitled to obedience, credit, or acceptance; determinate; commanding.
  

(a.)
Having an air of authority; positive; dictatorial; peremptory; as, an authoritative tone.
  

adj.
1. having weight or authority
سندي , مستند ,معتبر , پرماني
2. dictatorial
حاکمانہ