caudal vs postern

caudal

adj
  • Pertaining to the tail or posterior or hind part of a body. 

  • Toward the tail end (hind end) of the body; in bipeds such as humans, this direction corresponds to inferior. 

noun
  • A caudal vertebra. 

postern

adj
  • Situated at the rear; posterior. 

noun
  • A back gate, back door, side entrance, or other gateway distinct from the main entrance. 

  • A subterranean passage communicating between the parade and the main ditch, or between the ditches and the interior of the outworks. 

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