Old English lædere "one who leads, one first or most prominent," agent noun from lædan "to guide, conduct" (see lead (v.)). Cognate with Old Frisian ledera, Dutch leider, Old High German leitari, German Leiter. As a title for the head of an authoritarian state, from 1918 (translating Führer, Duce, caudillo, etc.). Meaning "writing or statement meant to begin a discussion or debate" is late 13c.; in modern use often short for leading article (1807) "opinion piece in a British newspaper" (leader in this sense attested from 1837). The golf course leader board so called from 1970.
1923, title assumed by Benito Mussolini (1883-1945), fascist leader of Italy; Italian, literally "leader," from Latin ducem, from PIE root *deuk- "to lead."
1610s, from Arabic, literally "leader; one who precedes," from amma "to go before, precede." As a high religious title used differently by Sunni and Shiite, but also used of the leader of daily prayers in the mosque and generally for a Muslim prince or religious leader. Related: Imamate.
c. 1600, "dictatorial" (a sense now restricted to authoritarian), earlier auctoritative (implied in auctoritativeli "with official approval or sanction"), from Medieval Latin auctoritativus, from Latin auctoritatem (see authority).
The meaning "having due authority, entitled to credence or obedience" is from 1650s; that of "proceeding from proper authority" is from 1809. Related: Authoritatively; authoritativeness.