cultivation vs weakening

cultivation

noun
  • The art or act of cultivating; improvement of land for or by agriculture 

  • Advancement or refinement in physical, intellectual, or moral condition 

  • The state of being cultivated or used for agriculture 

  • Devotion of time or attention to the improvement of (something) 

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 cultivation and weakening occurred in a corpus of books? (source: Google Ngram Viewer )