Dominus is the Latin word for master or owner. As a title of sovereignty the term under the Roman Republic had all the associations of the Greek Tyrannos; refused during the early principate, it finally became an official title of the Roman Emperors under Diocletian (this is where the term dominate, used to describe a political system of Roman Empire in 284-476, is derived from). Dominus, the French equivalent being "sieur", was the Latin title of the feudal, superior and mesne, lords, and also an ecclesiastical and academical title.