Source : Webster's Revised Unabridged Dictionary (1913)

Feudalism \Feu"dal*ism\, n. [Cf. F. f['e]odalisme.]
   The feudal system; a system by which the holding of estates
   in land is made dependent upon an obligation to render
   military service to the kind or feudal superior; feudal
   principles and usages.

Source : WordNet®

feudalism
     n : the social system that developed in Europe in the 8th C;
         vassals were protected by lords who they had to serve in
         war [syn: {feudal system}]