ancestor vs grandfather

ancestor

verb
  • To be an ancestor of. 

noun
  • One who had the same role or function in former times. 

  • One from whom an estate has descended;—the correlative of heir. 

  • One from whom a person is descended, whether on the father's or mother's side, at any distance of time; a progenitor; a forefather. 

  • An earlier type; a progenitor 

  • A word or phrase which serves as the origin of a term in another language. 

grandfather

verb
  • To be, or act as, a grandfather to. 

  • To retain discontinued laws or rules for (a thing, person or organization previously affected by them). 

noun
  • A father of someone's parent. 

  • A male forefather. 

  • The archived older version of a file that immediately preceded the father file. 

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