merestone vs terminus

merestone

noun
  • A stone designating a limit or boundary; a landmark. 

terminus

noun
  • A boundary or border, or a post or stone marking such a boundary. 

  • The end point of a transportation system, or the town or city in which it is located. 

  • The end or final point of something. 

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