progress vs weakening

progress

verb
  • To develop. 

  • To expedite. 

  • To move, go, or proceed forward; to advance. 

  • To improve; to become better or more complete. 

noun
  • Specifically, advancement to a higher or more developed state; development, growth. 

  • Movement onwards or forwards or towards a specific objective or direction; advance. 

  • An official journey made by a monarch or other high personage; a state journey, a circuit. 

  • Movement or advancement through a series of events, or points in time; development through time. 

  • Science has made extraordinary progress in the last fifty years. 

weakening

noun
  • A structural principle of mathematical logic that states that the hypotheses of any derived fact may be freely extended with additional assumptions. 

  • An instance or process of loss of strength. 

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