In the card game of bridge, the unusual notrump [1] is a conventional overcall showing a two-suited hand. It was originally devised by Al Roth in 1948 with Tobias Stone, [2] to show the minor suits after the opponents opened in a major.
The convention concept is now generally extended to show the "two lowest unbid" suits. Thus, over 1♣, 2NT shows diamonds and hearts; and over 1♦, it shows clubs and hearts. In addition to succinctly describing the hand to the partner, it deprives the opponents of bidding space, i.e. it has a preemptive effect. A drawback is that it provides the opponents with information about the strength and distribution of the overcaller's hand, potentially enabling improved declarer play should they secure the contract.
In his seminal 1953 book, [3] [4] The Roth-Stone System, Alvin Roth suggested that poor matchpoint scores usually result when the opponents are permitted to play low-level contracts and recommended protective bidding tactics for the player in the pass-out (balancing) seat in such auctions. [5]
He advocated use of weak jump overcalls and responses at a time when the standard practice was for jump overcalls and responses to show strong hands. [5] In one such application - when the opponents reach the two-level having bid only a major – he recommended an overcall of 2NT, as an artificial protective bid indicating, [5]
When an opponent opens the bidding with 1♥ or 1♠, the immediate overcall of 2NT shows at least 5–5 in the minor suits (that is, at least five clubs and at least five diamonds). If the right hand opponent (RHO) of the partner of the 2NT bid passes, that partner is expected to bid the minor suit that he prefers at the three-level. The unusual notrump applies the principle that when the natural meaning of a bid is not generally very useful, it is profitable to agree that it means something somewhat opposite. That is, while natural notrump bids show a strong hand with balanced distribution, the unusual notrump shows a weak hand with very unbalanced distribution.
If the 2NT bidder bids again freely, then it shows a strong two suiter. To distinguish the weak and strong holdings, many partnerships agree not to use the unusual notrump for intermediate hands (about 12 to 14 points); they would simply overcall with one of their suits and show the other later if the bidding offers a chance. However, for two-suiters, many players apply losing trick count (LTC) instead of point count, as it more accurately depicts the offensive trick-taking potential of the hand. With LTC in effect, the required strength is about 4.5–7 losers, the latter only in favorable vulnerability.
Similarly, a 4NT overcall shows an extreme two suiter (usually at least 6–5, often 6-6 or 7–6) and enough trick-taking potential so that a 5-level contract can be made, or a sacrifice will likely be profitable. It shows the same two suits as 2NT would show. Note that 4NT is "unusual" only when the opponents open the bidding; otherwise, 4NT is normally played as the Blackwood convention or a quantitative invitation to 6NT.
The Michaels cuebid is a similar convention which is used to show a two suiter with one or both major suits.
To counteract the unusual notrump, the opening side may employ unusual vs. unusual.
Recently, the Unusual 2NT has been used in opening seat showing a 5-5 minor suited hand and 7-11 HCP. The preemptive value of the two suited hand puts pressure on the opponents to find their fits, games and slams at the three level.
When the opponents open or overcall with an Unusual 2NT, defense uses a bidding scheme which incorporates two features:
After an Unusual 2NT overcall of a major:
| Opener | Overcaller | Responder | |
| Response | Meaning | ||
| 1♥ | 2NT | Dbl | looking to penalize, no primary major fit |
| 3♣ | good raise in hearts (8 losers or better) | ||
| 3♦ | sound values in spades at the three level or better | ||
| 3♥ | weak raise in hearts but stretched (8½ to 9 losers) | ||
| 3♠ | six spades, not forcing | ||
| 3NT | to play | ||
| 4♣ | splinter (singleton or void in clubs) in support of hearts | ||
| 4♦ | splinter (singleton or void in diamonds) in support of hearts | ||
| 1♠ | 2NT | Dbl | looking to penalize, no primary major fit |
| 3♣ | sound values in hearts at the three level or better | ||
| 3♦ | good raise in spades (8 losers or better) | ||
| 3♥ | six hearts, not forcing | ||
| 3♠ | weak raise in spades but stretched (8½ to 9 losers) | ||
| 3NT | to play | ||
| 4♣ | splinter (singleton or void in clubs) in support of spades | ||
| 4♦ | splinter (singleton or void in diamonds) in support of spades | ||
After an Unusual 2NT opening:
| Opener | Overcaller | |
| Response | Meaning | |
| 2NT | Dbl | able to penalize one of the minors or 20+ HCP |
| 3♣ | takeout for the majors, better hearts | |
| 3♦ | takeout for the majors, better spades | |
| 3♥ | single suited in hearts, opening hand values | |
| 3♠ | single suited in spades, opening hand values | |
Use of the convention with insufficient strength or lengths (such as 5–4 in the minors) may lead to:
Stayman is a bidding convention in the card game contract bridge. It is used by a partnership to find a 4-4 or 5-3 trump fit in a major suit after making a one notrump (1NT) opening bid and it has been adapted for use after a 2NT opening, a 1NT overcall, and many other natural notrump bids.
Standard American is a bidding system for the game of bridge widely used in North America and elsewhere. Owing to the popularization of the game by Charles Goren in the 1940s and 1950s, its early versions were sometimes referred to simply as 'Goren'. With the addition and evolution of various treatments and conventions, it is now more generally referred to as Standard American. It is a bidding system based on five-card majors and a strong notrump; players may add conventions and refine the meanings of bids through partnership agreements summarized in their convention card. One standardised version, SAYC, is widely used by casual partnerships and in online bridge.
Polish Club is a bridge bidding system which was developed in Poland, where it is the most popular bidding system, and which is also used by players of other countries. It is a type of small club system.
A bridge convention is an agreement about an artificial call or a set of related artificial calls. Calls made during the auction phase of a contract bridge game convey information about the player's card holdings. Calls may be "natural" or "artificial".
The Jacoby transfer, or simply transfers, in the card game contract bridge, is a convention in most bridge bidding systems initiated by responder following partner's notrump opening bid that forces opener to rebid in the suit ranked just above that bid by responder. For example, a response in diamonds forces a rebid in hearts and a response in hearts forces a rebid in spades. Transfers are used to show a long suit, usually a major, and to ensure that opener declare the hand if the final contract is in the suit transferred to, preventing the opponents from seeing the cards of the stronger hand.
The Michaels cuebid is a conventional bid used in the card game contract bridge. First devised by Michael Michaels of Miami Beach, FL, it is an overcaller's cuebid in opponent's opening suit and is normally used to show a two-suited hand with at least five cards in each suit and eight or more points.
These terms are used in contract bridge, using duplicate or rubber scoring. Some of them are also used in whist, bid whist, the obsolete game auction bridge, and other trick-taking games. This glossary supplements the Glossary of card game terms.
In the card game contract bridge, a takeout double is a low-level conventional call of "Double" over an opponent's bid as a request for partner to bid his best of the unbid suits. The most common takeout double is after an opponent's opening bid of one of a suit where the double shows a hand with opening values, support for all three unbid suits and shortness in the suit doubled. Normally, the partner of the doubler must bid his best suit but may pass if (a) his right hand opponent intervenes or (b) on the more rare occasions when his hand is such that he wishes to convert the takeout double to a penalty double.
In the card game contract bridge, DONT is a conventional overcall used to interfere with an opponent's one notrump (1NT) opening bid. DONT, an acronym for Disturb Opponents' Notrump, was designed by Marty Bergen, and is therefore also referred to as "Bergen over Notrump". Although the method is often criticized for being too nebulous, it remains fairly popular. The convention was first published in the September/October 1989 issue of Bridge Today.
The Raptor 1NT overcall over an opposing 1-level suit opening is a contract bridge convention that indicates a two-suited hand with exactly four cards in the unbid major and a longer suit in an unbid minor.
In the game of bridge, Ghestem is a conventional overcall structure, using 2NT, 3♣, and the (non-jump) cuebid over an opposing opening at the one level to denote two-suited hands in two of the remaining three suits.
In contract bridge, an overcall is a bid made after an opening bid has been made by an opponent; the term refers only to the first such bid. A direct overcall is such a bid made by the player seated immediately to the left of the opener, i.e. next in the bidding rotation; an overcall in the 'last seat', i.e. by the player to the right of opener, which is made after two intervening passes, is referred to as a balancing or protective overcall.
Suction is a contract bridge bidding convention used to intervene over an opponent's 1NT opening. Using the suction convention, a suit overcall of a 1NT opening is conventional and denies the suit actually bid. It shows either:
EHAA is a highly natural bidding system in contract bridge characterized by four-card majors, sound opening bids, undisciplined weak two-bids in all four suits and a mini notrump, usually of 10–12 high card points.
Inverted minors refers to a treatment introduced by the Kaplan–Sheinwold (K–S) bidding system for the popular card game bridge. The original structure of Precision, another bidding system, also employed inverted minors over a 1♦ opening. However, the treatment is no longer restricted to users of these bidding systems. although partnerships that use a Short club system tend also to use the convention only after a 1♦ opener.
New Minor Forcing (NMF), is a contract bridge bidding convention used to find a 5-3 or 4-4 major suit fit after a specific sequence of bids in which opener has rebid one notrump. The convention is triggered by responder at his second turn by an artificial bid of two in an unbid minor; it requires that he hold five cards in the major he has previously bid and an unlimited hand ranging in value from at least game invitational strength to that sufficient to have interest in slam; he may also hold four cards in the other major. Accordingly, there are six bidding sequences in which the New Minor Forcing bid may be applied:
The Baron bidding system in contract bridge was developed in England in the 1940s as a variant of Acol and incorporates several conventions including the Baron Three Clubs, the Baron Notrump Overcall, the Baron Two Notrump Response and the Baron Two Spades and Three Spades.
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Unusual vs. unusual is a competitive bidding convention used in contract bridge by the opening side after an opponent has made an overcall showing two suits.
Astro is a contract bridge bidding convention used to intervene over an opponent's one notrump (1NT) opening bid. The name is derived from the initials of the surnames of its inventors - Paul Allinger, Roger Stern and Lawrence Rosler.