That area of land required for the service of one *knight. This was the essence of the obligation of military service in the 12c and 13c. Land was granted by a *tenant-in-chief to a knight, who would answer the king's summons to provide a certain number of men. Their customary obligation was to serve for 40 days each year without pay. In the 12c, *scutage appeared, by which the king raised money in lieu of military service. -
Cf. Fief
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.