deathblow vs manslaughter

deathblow

noun
  • A strike or blow that leads to death, especially a coup de grace. 

  • Something that prevents the completion, or ends the existence, of a project etc.; a fatal setback. 

manslaughter

noun
  • The unlawful killing of a human, either in negligence or incidentally to the commission of some unlawful act, but without specific malice, or upon a sudden excitement of anger; considered less culpable than murder, but more culpable than justifiable homicide. 

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