certifiably vs downright

certifiably

adv
  • Genuinely 

  • With the potential for certification. 

  • To a great extent. 

  • Undoubtedly, demonstrably. 

downright

adv
  • Really; actually; quite 

adj
  • Directly to the point; plain 

  • Using plain direct language; accustomed to express opinions directly and bluntly; blunt. 

  • Complete; absolute 

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