above-board vs treacherous

above-board

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

adv
  • Honestly; openly. 

treacherous

adj
  • Deceitful; inclined to betray. 

  • Unreliable; dangerous. 

  • Exhibiting treachery. 

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