fraternity vs tribus

fraternity

noun
  • The quality of being brothers or brotherly; brotherhood. 

  • A group of people associated for a common purpose. 

  • A social organization of male students at a college or university; usually identified by Greek letters. 

tribus

noun
  • Synonym of tribe 

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