grandchild vs papa

grandchild

noun
  • A child of someone's child. 

papa

noun
  • A pet name for one's grandfather. 

  • A parish priest in the Greek Orthodox Church. 

  • Dad, daddy, father; a familiar or old-fashioned term of address to one’s father. 

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