discontinuity vs protraction

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. 

protraction

noun
  • The condition of being protracted 

  • The act of making a plot on paper. 

  • The lengthening of a short syllable 

  • An anterior movement on the horizontal plane; The forward movement of the tongue or of a limb 

  • The act of protracting 

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