authoritative

This term carries a dual sense of reliability and power. When describing a source or a document, it suggests an unmatched level of accuracy and expertise, implying that the information is definitive and beyond reasonable doubt. When applied to a person's demeanor or voice, it describes a quality of command that naturally compels others to listen or obey. This is distinct from being authoritarian, which implies a harsh or tyrannical exercise of power; authoritative instead suggests a legitimate, confident, and respected leadership style.