hash mark vs straightedge

hash mark

noun
  • One of the parallel lines on either side of the face-off circles. 

  • A service stripe, as on an enlistee’s uniform sleeve. 

  • An inbounds line. 

  • The hash or pound sign (#). 

straightedge

noun
  • A flat, rectangular tool used to draw, cut or check the straightness of straight lines. 

adj
  • Living one's life opposing or eschewing the use of substances such as alcohol, tobacco, and drugs. 

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