François Louis Ganshof in the context of "Feudal"

Feudalism, also known as the feudal system, was a combination of legal, economic, military, cultural, and political customs that flourished in medieval Europe from the 9th to 15th centuries. Broadly defined, it was a way of structuring society around relationships derived from the holding of land in exchange for service or labour.

The classic definition, by François Louis Ganshof (1944), describes a set of reciprocal legal and military obligations of the warrior nobility and revolved around the key concepts of lords, vassals, and fiefs. A broader definition, as described by Marc Bloch (1939), includes not only the obligations of the warrior nobility but the obligations of all three estates of the realm: the nobility, the clergy, and the peasantry, all of whom were bound by a system of manorialism; this is sometimes referred to as a "feudal society".