The word is derived from the Latin dominus, meaning lord or master, as an owner versus his slave — this had been used sycophantically to address emperors from the Julio-Claudian (first) dynasty on, but not used by them as a style — Tiberius in particular is said to have reviled it openly. It became common under Diocletian, who is therefore a logical choice as the first ruler of the 'early' dominate. Historian David Potter describes the transformation of Government under Diocletian when describing the shifts in imagery the Emperor used to display his power (in this case the building of a huge new palace at Sirmium):
The style of Government so memorably described by Marcus, whereby the emperor sought to show himself as a model of correct aristocratic deportment, had given way to a style in which the emperor was seen to be distinct from all other mortals. His house could no longer be a grander version of houses that other people might live in: it, like him, had to be different.
The first phase of Imperial government, known as the Principate, when the formalities of the constitutionally-never-abolished republic were still very much the 'politically correct' image, has also often been said to have ended after the Third Century Crisis of 235–284, which concluded when Diocletian established himself as Emperor. Moving the notion of the Emperor away from the republican forms of the Empire's first three centuries, Diocletian introduced a novel system of joint rule by four, the tetrarchy, and he and his colleagues and his successors (in two imperial territories, east and west, not four) chose to stop using the title princeps, instead openly displaying the naked face of Imperial power and adopting a Hellenistic style of government more influenced by the veneration of the Eastern potentates of ancient Egypt and Persia than by the heritage of civic collegiality amongst the governing class passed down from the days of the 'uncrowned' Roman Republic.