approval vs flattery

approval

noun
  • An expression of favorable acceptance and encouragement; a compliment that also condones. 

  • Something mailed by a seller to a collector to match their stated interests; the collector can approve of or return the item. 

  • An expression granting permission; an indication of agreement with a proposal; an acknowledgement that a person, thing, or event meets requirements. 

flattery

noun
  • Excessive praise or approval, which is often insincere and sometimes contrived to win favour. 

  • An instance of excessive praise. 

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