flak vs invective

flak

noun
  • Adverse criticism. 

  • A public-relations spokesperson. 

  • Anti-aircraft shell fire. 

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

invective

noun
  • A harsh or reproachful accusation. 

  • Something spoken or written, intended to cast shame, disgrace, censure, or reproach on another. 

  • A severe or violent censure or reproach. 

  • An expression which inveighs or rails against a person. 

adj
  • Characterized by invection or railing. 

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