disapprobation vs flak

disapprobation

noun
  • An act or expression of condemnation or disapproval, especially on moral grounds. 

flak

noun
  • Adverse criticism. 

  • A public-relations spokesperson. 

  • Anti-aircraft shell fire. 

  • Ground-based anti-aircraft guns firing explosive shells. 

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