certainly vs obviously

certainly

adv
  • In a way which is certain; with certainty. 

  • An emphatic affirmative answer; of course. 

  • Without doubt, surely. 

obviously

adv
  • In an obvious or clearly apparent manner. 

  • Used as a filler word, or to introduce information even when not obvious. 

  • She was in floods of tears and obviously very upset. 

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