Authoritative

• (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.
Found on http://thinkexist.com/dictionary/meaning/authoritative/

authoritative

authorized adjective sanctioned by established authority; `an authoritative communique`; `the authorized biography`
Found on https://www.encyclo.co.uk/local/20974

Authoritative

Au·thor'i·ta·tive adjective 1. Having, or proceeding from, due authority; entitled to obedience, credit, or acceptance; determinate; commanding. « The sacred functions of authoritative teaching. Barrow. » 2. Having an air of authority; positive; dictatori...
Found on http://www.encyclo.co.uk/webster/A/148

authoritative

[adj] - of recognized authority or excellence 2. [adj] - having authority or ascendancy or influence 3. [adj] - sanctioned by established authority
Found on http://www.webdictionary.co.uk/definition.php?query=authoritative
No exact match found