Source : Webster's Revised Unabridged Dictionary (1913)

Trierarch \Tri"er*arch\, n. [L. trierarchus, Gr. ?; ? a trireme
   + ? a leader, a chief.] (Gr. Antiq.)
      (a) The commander of a trireme.
      (b) At Athens, one who (singly, or jointly with other
          citizens) had to fit out a trireme for the public
          service.