certifiably vs incredibly

certifiably

adv
  • To a great extent. 

  • With the potential for certification. 

  • Undoubtedly, demonstrably. 

  • Genuinely 

incredibly

adv
  • To a great extent; extremely. 

  • In an incredible manner; not to be believed. 

  • Used to note the surprising or hard-to-believe nature of what is being said and suggest that it is nevertheless true. 

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