discontinuity vs rima

discontinuity

noun
  • A lack of continuity, regularity or sequence; a break or gap. 

  • a subterranean interface at which seismic velocities change 

  • A point in the range of a function at which it is undefined or discontinuous. 

rima

noun
  • A cleft or gap between two symmetrical parts, particularly between the vocal folds. 

  • A crack or fissure on a lunar or planetary surface; a rille. 

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