certifiably vs undoubtably

certifiably

adv
  • Undoubtedly, demonstrably. 

  • With the potential for certification. 

  • To a great extent. 

  • Genuinely 

undoubtably

adv
  • Without doubt; indubitably, undoubtedly. 

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