The entu was the senior priestess in the service of a major Mesopotamian god, most famously the moon god Nanna at Ur, and the office was reserved for women of the highest social standing, typically a king's own daughter. The role was conceived as a kind of sacred marriage: the entu was installed as the ceremonial consort of the god she served, resided in a dedicated temple complex, the gipar, adjacent to his main sanctuary, and took on ritual and administrative duties that extended well beyond devotional worship into the management of substantial temple estates, land, herds and dependent labour that a major Mesopotamian temple controlled as an economic institution in its own right.
Appointing a royal daughter to the office let a king extend his political reach directly into a rival or newly conquered city's religious establishment without displacing the existing cult, since the entu served the city's own patron deity rather than importing a foreign one. Sargon of Akkad used exactly this strategy when he installed his daughter Enheduanna as entu of Nanna at Ur shortly after conquering the Sumerian south, a move later scholarship reads as a deliberate act of religious and political integration binding the newly unified territory together through his family's presence in its most prestigious priesthood.