behead vs decollate

behead

verb
  • To deliberately remove the head of; to cut off (someone's) head. 

decollate

verb
  • To behead. 

  • To separate the copies of a multipart computer printout. 

adj
  • Tapering to a blunt end. 

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