heir-at-law vs predecessor

heir-at-law

noun
  • A person legally entitled to inherit the property of someone who dies intestate. 

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 Usually used to describe an earlier, outdated model.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-at-law and predecessor occurred in a corpus of books? (source: Google Ngram Viewer )