indicator vs straightedge

indicator

noun
  • The needle or dial on such a meter. 

  • Any of many substances, such as litmus, used to indicate the concentration of a substance, or the degree of a reaction. 

  • A plant or animal whose presence is indicative of some specific environment. 

  • A turn signal; each of the flashing lights on each side of a vehicle which indicate a turn is being made to left or right, or a lane change etc. 

  • A pointer or index that indicates something. 

  • A measure, such as unemployment rate, which can be used to predict economic trends. 

  • A bird, the honeyguide. 

  • A meter or gauge. 

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 indicator and straightedge occurred in a corpus of books? (source: Google Ngram Viewer )