adverse possession vs fief

adverse possession

noun
  • A means of acquiring title to another's real property without compensation by occupying the property in a manner that has under common law the requirements of being actual, open and notorious, exclusive, hostile, under cover of claim or right, and continuous for a certain number of years. 

fief

noun
  • Synonym of estate: any land, when considered as a region over which the owner exercises lordly control. 

  • A territory, a domain, an area over which one exercises lordly control, particularly with regard to corporate or governmental bureaucracies. 

  • Land held of a superior, particularly on condition of homage, fealty, and personal service, especially military service. 

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