above-board vs thorough

above-board

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

adv
  • Honestly; openly. 

thorough

adj
  • Painstaking and careful not to miss or omit any detail. 

  • Utter; complete; absolute. 

noun
  • A furrow between two ridges, to drain off the surface water. 

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