Definition of Feudal system
The system of feuds. A political and social system which prevailed throughout Europe during the eleventh, twelfth, and thirteenth centuries, and is supposed to have grown out of the peculiar usages and policy of the Teutonic nations who overran the continent after the fall of the Western Roman Empire, as developed by the exigencies of their military domination, and possibly furthered by notions taken from the Roman jurisprudence.
It was introduced into England, in its completeness, by William I, A.D. 1086, though it may have existed in a rudimentary form among the Saxons before the Conquest. It formed the entire basis of the real-property law of England in medieval times; and survivals of the system, in modern days, so modify and color that branch of jurisprudence, both in England and America, that many of its principles require for their complete understanding a knowledge of the feudal system. The feudal system originated in the relations of a military chieftain and his followers, or king and nobles, or lord and vassals, and especially their relations as determined by the bond established by a grant of land from the former to the latter. From this it grew into a complete and intricate complex of rules for the tenure and transmission of real estate, and of correlated duties and services; while, by tying men to the land and to those holding above and below them, it created a close-knit hierarchy of persons, and developed an aggregate of social and political institutions.
That's the definition of Feudal system in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.