Auctoritas is a Latin word and is the origin of English "authority." While historically its use in English was restricted to discussions of the political history of Rome, the beginning of phenomenological philosophy in the 20th century expanded the use of the word.
In ancient Rome, Auctoritas referred to the general level of prestige a person had in Roman society, and, as a consequence, his clout, influence, and ability to rally support around his will. Auctoritas was not merely political, however; it had a numinous content and symbolized the mysterious "power of command" of heroic Roman figures.
Read more about Auctoritas: Etymology and Origin, Political Meaning in Ancient Rome, Middle Ages, Hannah Arendt, Giorgio Agamben