Tetrarch ,
n. [L. tetrarches, Gr. >, >; τέτρα- (see Tetra-) + > a ruler, > to lead; rule: cf. F. tétrarque. See Arch, a.] (Rom. Antiq.) A Roman governor of the fourth part of a province; hence, any subordinate or dependent prince; also, a petty king or sovereign.1913 Webster