descending vs retrogradation

descending

noun
  • A descent. 

adj
  • Ordered such that each element is less than or equal to the previous element. 

  • Moving or sloping downwards. 

  • Becoming lower in pitch. 

  • Causing a sequence to follow a descending order. 

retrogradation

noun
  • Decline, degradation. 

  • A reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves, largely responsible for bread becoming stale. 

  • Motion in a retrograde manner. 

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