flatly vs insipidly

flatly

adv
  • In a manner that shows no emotion. 

  • In a definite manner; in a manner showing complete certainty. 

  • In a physically flat or level manner. 

insipidly

adv
  • In an insipid manner. 

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