first-degree murder vs killing

first-degree murder

noun
  • An act that constitutes the crime of first-degree murder. 

  • The criminal offence of murder in a form considered by law to be the most serious; the precise distinction may vary by jurisdiction but typically involves premeditation, or the choice of victim or other circumstances being regarded as especially blameworthy. 

killing

noun
  • An instance of someone being killed. 

  • A large amount of money. 

adj
  • That makes one ‘die’ with laughter; very funny. 

  • That literally deprives of life; lethal, deadly, fatal. 

How often have the words first-degree murder and killing occurred in a corpus of books? (source: Google Ngram Viewer )