Definition of "headstone"

headstone

noun
plural headstones
1. A gravestone, a grave marker: a monument traditionally made of stone placed at the head of a grave.
  Quotations
  He called the contractor and ordered a replacement headstone with a new inscription.
  2020, Akwaeke Emezi, The Death of Vivek Oji, Faber & Faber Ltd, page 227
2. The cornerstone or principal stone of a building.