This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
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adj. Having or arising from authority; official: an authoritative decree; authoritative sources.

adj. Of acknowledged accuracy or excellence; highly reliable: an authoritative account of the revolution.

adj. Wielding authority; commanding: the captain's authoritative manner.

adj. Arising or originating from a figure of authority

adj. Highly accurate or definitive; treated or worthy of treatment as a scholarly authority

adj. Having a commanding style.

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

adj. Having an air of authority; positive; dictatorial; peremptory.

Having due authority; having the sanction or weight of authority; entitled to credence or obedience: as, “authoritative teaching,” Barrow.

Having an air of authority; positive; peremptory; dictatorial.

Synonyms Authoritative, Magisterial, etc. (see magisterial), commanding.

adj. having authority or ascendancy or influence

adj. of recognized authority or excellence

adj. sanctioned by established authority

"The state-run Xinhua News Agency said Thursday that foreign media reports that Mr. Jiang has died are "pure rumor," citing what it called "authoritative sources.""

influential    standard    official   

authoritatively    authoritativeness   

determinate    commanding    positive    dictatorial    peremptory    of record    definitive    proper    precise   

comprehensive    concise    authentic    decisive    imperious    logical    impartial    forceful    explicit    trustworthy