recession vs weakening

recession

noun
  • The act or an instance of receding or withdrawing. 

  • A procedure in which an extraocular muscle is detached from the globe of the eye and reattached posteriorly. 

  • A period of low temperatures that causes a reduction in species; ice age. 

  • A period of reduced economic activity 

  • The ceremonial filing out of clergy and/or choir at the end of a church service. 

  • The act of ceding something back. 

weakening

noun
  • An instance or process of loss of strength. 

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

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