headspring vs primal

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. 

primal

verb
  • To take part in primal therapy. 

noun
  • A primal cut (of meat). 

adj
  • Being the first in time or in history. 

  • Of greatest importance; primary. 

  • Being one of the pieces of meat initially separated from the carcass during butchering, prior to division into smaller cuts. 

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