decollation vs impalement

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. 

impalement

noun
  • The act of torturing or executing someone by impaling them on a sharp stake. 

  • (obsolete) In the sense of an enclosure, the calyx of a flower. In still older works, also spelt empalement (q.v.) 

  • A space fenced in, such as by palings, possibly in the form of an enclosure or cup. 

  • The joining of two coats of arms on one shield. 

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