Definition
A board card that doesn’t improve any player’s hand and gives them no additional outs. For example, if one player holds Kh Ah, another holds 5d 6c, and the board is 4h 7h Jc, then a 2s on the turn is a blank. This card did not help the first player make a flush or the second player make a straight, did not give either of them a pair, and therefore did not improve their hands.