feudalism vs thrall

feudalism

noun
  • A social system based on personal ownership of resources and personal fealty between a suzerain (lord) and a vassal (subject). Defining characteristics are direct ownership of resources, personal loyalty, and a hierarchical social structure reinforced by religion. 

thrall

noun
  • The state of being under the control of another person. 

  • One who is enslaved or under mind control. 

  • A shelf; a stand for barrels, etc. 

verb
  • To make a thrall; enslave. 

How often have the words feudalism and thrall occurred in a corpus of books? (source: Google Ngram Viewer )