nates vs nether cheeks

nates

noun
  • The buttocks. 

  • The umbones of a bivalve shell. 

  • The two anterior of the four lobes on the dorsal side of the midbrain of most mammals; the anterior optic lobes. 

nether cheeks

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