cycloid vs ringlike

cycloid

adj
  • Resembling a circle; cycloidal. 

  • characterized by alternating high and low moods. 

  • Thin and rounded, with smooth edges. 

noun
  • A fish having cycloid scales. 

  • The locus of a point on the circumference of a circle that rolls without slipping on a fixed straight line. 

ringlike

adj
  • Like a ring; round or nearly so. 

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