above board

adjective

he had set up a chain of more or less above-board casinos:

honest, fair, open, frank, straight, overt, candid, forthright, unconcealed, trustworthy, unequivocal;

legal, legitimate, lawful, licit;

informal legit, kosher, by the book, fair and square, square, on the level, on the up and up, upfront;

British, informal pukka.

▷antonyms dishonest, shady.

adverb

it's imperative that you play it all above board:

honestly, fairly, openly, frankly, overtly, candidly, forthrightly, unequivocally;

legally, legitimately, lawfully.

▷antonyms dishonestly, shadily.

above board Oxford Dictionary of English