authoritative
1. [ adjective ] having authority or ascendancy or influence
Synonyms: important
Examples:

"an important official" "the captain's authoritative manner"

Related terms: influential
2. [ adjective ] sanctioned by established authority
Synonyms: authorized authorised
Examples:

"an authoritative communique" "the authorized biography"

Related terms: official
3. [ adjective ] of recognized authority or excellence
Synonyms: classical definitive
Examples:

"the definitive work on Greece" "classical methods of navigation"

Related terms: standard
4. [ adjective ] sanctioned by established authority
Synonyms: authorized
Examples:

"an authoritative communique" "the authorized biography"

Related terms: official
Similar spelling:   authoritatively
  authorities
  authoritarian
  authoritarianism
  authority_figure