heir vs predecessor

heir

verb
  • To inherit. 

noun
  • A successor in a role, representing continuity with the predecessor. 

  • Someone who inherits, or is designated to inherit, the property of another. 

  • One who inherits, or has been designated to inherit, a hereditary title or office. 

predecessor

noun
  • A model or type of machinery or device which precedes the current (or later) one. Usually used to describe an earlier, outdated model. 

  • One who precedes; one who has preceded another in any state, position, office, etc.; one whom another follows or comes after, in any office or position. 

  • A vertex having a directed path to another vertex 

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