authorization vs flak

authorization

noun
  • (A document giving) formal sanction, permission or warrant. 

  • Permission. 

  • Permission, possibly limited, to spend funds for a specific budgetary purpose. 

  • An act of authorizing. 

flak

noun
  • A public-relations spokesperson. 

  • Anti-aircraft shell fire. 

  • Adverse criticism. 

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

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