authoritative
/ɔːˈθɒɹɪtətɪv/adjective
-
Arising or originating from a figure of authority
"The authoritative rules in this school come not from the headmaster but from the aged matron."
-
Highly accurate or definitive; treated or worthy of treatment as a scholarly authority
"This book is the world's most authoritative guide to insect breeding habits."
-
Having a commanding style.
"He instructed us in that booming, authoritative voice of his."
Synonyms:
of record, definitive, precise, proper