arcdegree vs diameter

arcdegree

noun
  • A unit of measurement of angle equal to ¹⁄₃₆₀ of a circle's circumference. 

diameter

noun
  • Any straight line between two points on the circumference of a circle that passes through the centre/center of the circle. 

  • The maximum eccentricity over all vertices in a graph. 

  • The length of such a line. 

  • The maximum distance between any two points in a metric space 

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