flak vs stricture

flak

noun
  • Adverse criticism. 

  • A public-relations spokesperson. 

  • Anti-aircraft shell fire. 

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

stricture

noun
  • A sternly critical remark or review. 

  • The degree of contact, in consonants. 

  • Abnormal narrowing of a canal or duct in the body. 

  • A general state of restrictiveness on behavior, action, or ideology. 

  • A rule restricting behaviour or action. 

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