taoiseach
Definitions (by source)
m., chief, leader.
Stories from Keating's History of Ireland. Editor: Osborn Bergin.
m., chieftain, leader, 259, 2807;--pl. –sigh, 6610
Trí Bior-Ghaoithe an Bháis: The Three Shafts of Death. Editor: Osborn Bergin.