au ‧ thor ‧ i ‧ ta ‧ tive AC /ɔːˈθɒrətətɪv, ɔːˈθɒrɪtətɪv, ə- $ ɒːˈθɑːrəteɪtɪv, əˈθɔː-/ BrE AmE adjective
[ Word Family: noun : ↑ authority , ↑ authorization , ↑ authoritarian , ↑ authoritarianism ; adjective : ↑ authoritarian , ↑ authoritative , authorized ≠ ↑ unauthorized ; verb : ↑ authorize ; adverb : ↑ authoritatively ]
1 . an authoritative book, account etc is respected because the person who wrote it knows a lot about the subject:
the most authoritative work on English surnames
2 . behaving or speaking in a confident determined way that makes people respect and obey you:
He has a commanding presence and an authoritative voice.
—authoritatively adverb