quadrilateral vs trapezium

quadrilateral

noun
  • A polygon with four sides. 

  • An area defended by four fortresses supporting each other. 

adj
  • Having four sides. 

trapezium

noun
  • A quadrilateral with two sides parallel. 

  • The trapezium bone of the wrist. 

  • A region on the ventral side of the brain, either just back of the pons Varolii, or, as in man, covered by the posterior extension of its transverse fibers. 

  • A quadrilateral with two sides parallel and two sides non-parallel. 

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