empire

Empire is derived from the Latin noun imperium which denotes the absolute authority of a Roman magistrate over those under him.

As Rome's power grew, Romans began applying the word imperium Romanum to the territory, taken as a whole, over which Rome held absolute authority. This later sense of imperium gave rise to the modern term "empire." Strangely, the term emperor as "ruler of an empire" is not directly derived from the Latin noun imperator, but rather a back-formation from "empire."

My working definition of empire is "a large multi-ethnic state and/or a grouping of regions ruled by a coercive central authority." The "and/or" distinction is crucial.

"Multi-ethnic state" can refer to the center of the empire itself and the territory immediately contiguous: Italy (Rome); Eastern Europe/Western Asia (Russia); Southern and Central North America (USA). The internal ethnic differences can be more (Russia) or less (Rome, USA) pronounced; more important is that the state itself can be construed as a geographical "heartland."

"Grouping of regions" can include neighboring regions: Sicily (Rome); Siberia (Russia); Mexico Territory (USA). It can also include peripheral and far-off regions: Britain (Rome); Alaska (Russia); Hawaii (USA).

Empire can be achieved through imperialistic warfare or by appropriating Terra Nullius.