An authoritative source is a person, organization, or document that is reliable and trustworthy when providing information or knowledge on a specific topic. Full definition
On the one hand, women are encouraged to view the medical profession as the most authoritative source of information and advice. (newscientist.com)
It's probably not a good idea to take action movies as authoritative sources on the law. (law.stackexchange.com)
In response, we gathered 2017 mortgage rate predictions from the most authoritative sources, averaging them for the most accurate forecast possible. (themortgagereports.com)