The Collaborative International Dictionary of English v.0.48:

Archon \Ar"chon\, n. [L. archon, Gr. ?, ?, ruler, chief
   magistrate, p. pr. of ? to be first, to rule.] (Antiq.)
   One of the chief magistrates in ancient Athens, especially,
   by pre["e]minence, the first of the nine chief magistrates.
   -- Ar*chon"tic, a.
   [1913 Webster]