Final answer:
A fief was the land given by a king to a noble under the feudal system, in exchange for military service and other obligations.
Step-by-step explanation:
The land that was given by the king to a noble was called a fief. This practice was a central element of the feudal system, which was a social and economic structure that emerged during the 9th century in medieval Europe. Under this system, a lord would grant a piece of land known as a fief to a vassal in exchange for military service and other duties. In turn, vassals would pledge their loyalty to their lord in a ceremony known as a pledge of fealty. The land provided resources to vassals, enabling them to support themselves and fulfill their obligations to their lord, such as acquiring horses, armor, and weapons. Fiefs were hereditary, passing from generation to generation, and vassals had the right to extract wealth from the land and the peasants who lived on it.