certainly vs clearly

certainly

adv
  • Without doubt, surely. 

  • In a way which is certain; with certainty. 

  • An emphatic affirmative answer; of course. 

clearly

adv
  • Without a doubt; obviously. 

  • To a degree clearly discernible. 

  • In a clear manner. 

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