A special conventional bid in the game of bridge (see bridge bidding). Not everyone plays this convention, but it is really useful and most partnerships use it once they learn what it is. The agreement applies in the following circumstances:
- Your partner opens one of a suit
- The next player to bid, your RHO, bids a different suit at or below the three-level
- You make a bid of double.
It really only counts in these exactcircumstances - if RHO overcalls one notrump and you think your double is a negative double, you can reasonably be accused of talking nonsense. You'd be surprised how many people don't get that.
Now that you know how to make a negative double, you're wondering what it all means. Your double promises partner exactly four cards in any unbid major suits, and enough points to justify making your partner bid at the next level. This is generally around 6-10 HCP, depending on how high the bidding has gotten so far. Do not make this bid if you have four hearts and five spades. Do not make this bid just because you think double is a cool bid.
Or, if both majors have been bid already, your double shows tolerance for both minors or
Note that this bid makes for some interesting negative inferences. Now, if partner opens, RHO overcalls, and you bid a major, partner knows you don't have exactly four or you'd have made a negative double. So we define that bid to mean five cards.