Source : Webster's Revised Unabridged Dictionary (1913)

Tetrarchy \Tet"rarch*y\, n.; pl. {Tetrarchies}. [L. tetrarchia,
   Gr. ?: cf. F. t['e]trarchie.] (Rom. Antiq.)
   The district under a Roman tetrarch; the office or
   jurisdiction of a tetrarch; a tetrarchate.