enhancement vs weakening

enhancement

noun
  • An improvement or supplement that tends to increase a sense of esteem. 

  • The degree to which the image of a scan stands out as a bright area. 

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