The ecumene (US) or oecumene (UK; , oikouméne,  "inhabited") was an ancient Greek term for the known world, the inhabited world, or the habitable world. Under the Roman Empire, it came to refer to the civilized world and the secular and religious imperial administration. In present usage, it is used as the noun form of "ecumenical" and describes the Christian Church as a unified whole or the unified modern world civilization. It is also used in cartography to describe a type of world map (mappa mundi) used in late Antiquity and the Middle Ages.