above-board vs certainly

above-board

adv
  • Honestly; openly. 

adj
  • In open sight; without trick, concealment, or deception. 

certainly

adv
  • Without doubt, surely. 

  • In a way which is certain; with certainty. 

  • An emphatic affirmative answer; of course. 

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