in open sight; without tricks, concealment, or disguise: Their actions are open and aboveboard.
Origin: 1610–20; above+ board; so called from the requirement of keeping the hands above the table or board in order to discourage possible cheating at cards
a·bove·board (ə-bŭv'bôrd', -bōrd') adv.
& adj. Without deceit or trickery; straightforward.
[Originally a gambling term referring to the fact that a gambler whose hands were above the board or gaming table could not engage in trickery, such as changing cards, below the table.]