Nut straight

The best possible straight for a given situation. It must not be the nut hand overall. For example, if the board in hold'em is 5♥ 8♥ 6♠ 5♣ J♥ and you have 7♦ 9♦, your straight five to nine is the nut straight but your opponent could hold A♥ K♥ for the nut flush.