epitaph vs headstone

epitaph

noun
  • An inscription on a gravestone in memory of the deceased. 

  • A poem or other short text written in memory of a deceased person. 

verb
  • To write or speak after the manner of an epitaph. 

  • To commemorate by an epitaph. 

headstone

noun
  • A gravestone, a grave marker: a monument traditionally made of stone placed at the head of a grave. 

  • The cornerstone or principal stone of a building. 

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