decapitation vs decollation

decapitation

noun
  • Beheading; the act of beheading or decapitating. 

  • The ousting or destruction of the ruling body of a government or other organization. 

  • The unseating of a senior politician. 

decollation

noun
  • The act of beheading someone. 

  • The festival of the Baptist, celebrated on 29 August. 

  • A picture of a decapitation, especially of the head of St John the Baptist on a charger. 

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