1. (

• authoritative ,
• important

) having authority or ascendancy or influence; "an important official"; "the captain's authoritative manner" ;

2. (

• authoritative ,
• definitive

) of recognized authority or excellence; "the definitive work on Greece" ;

3. (

• authoritative ,
• authorized ,
• authorised

) sanctioned by established authority; "an authoritative communique"; "the authorized biography" ;