Term that emerged in the 17th century that has been used to describe economic, legal, political, social, and economic relationships in the European Middle Ages. Derived from the Latin word feudum (fief) but unknown to people of the Middle Ages, the term feudalism has been used most broadly to refer to medieval society as a whole, and in this way may be understood as a socio-economic system that is often called manorialism. It has been used most narrowly to describe relations between lords and vassals that involve the exchange of land for military service. Feudalism in this sense is thought to have emerged in a time of political disorder in the 11th century as a means to restore order, and it was later a key element in the establishment of strong monarchies. Feudalism also has been applied, often inappropriately, to non-Western societies where institutions similar to those of medieval Europe are thought to have existed. The many ways feudalism has been used have drained it of specific meaning, however, and caused some scholars to reject it as a useful concept for understanding medieval society.