auger vs countersink

auger

noun
  • A tool used to bore holes in the ground, e.g. for fence posts 

  • A snake or plumber's snake (plumbing tool). 

  • A hollow drill used to take core samples of soil, ice, etc. for scientific study. 

  • A carpenter's tool for boring holes longer than those bored by a gimlet. 

verb
  • To use an auger; to drill a hole using an auger. 

  • To proceed in the manner of an auger. 

countersink

noun
  • a cylindrical recess, typically machined around a hole to admit a screw so that it sits flush with a surface. 

verb
  • To create such a conical recess. 

  • To cause to sink even with or below the surface. 

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