decollate vs headspring

decollate

verb
  • To behead. 

  • To separate the copies of a multipart computer printout. 

adj
  • Tapering to a blunt end. 

headspring

verb
  • To perform a headspring. 

noun
  • A move in which the gymnast places both hands on the mat with the top of the head about 6 inches in front, pushes off with the hands while flipping the legs overhead, and lands on the feet. 

  • A fountainhead; a source. 

  • A basis or foundation. 

  • A spring that sits at the top of a mechanism, pushing the internal parts inward. 

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