backgammon glossary

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Accept A Double: See
Take

Ace Point: A player's 1 point.
Ace Point Game: When a player is trapped on the opponent's ace point and remains there in the hope of hitting a blot as the opponent brings his checkers home and bears them off.
Action Play: A play designed to provoke an exchange of hits, most often used after the opponent has escaped his runners.
Active Builder: A checker that is completely free to make another point.
Advanced Anchor: An anchor located on the opponent's 4 or 5 point, or in the opponent's outer board.
Anchor: A point occupied by two or more of a player's checkers on the opponent's side of the board.
Attacking Game: See Blitz.
Automatic Doubles: An optional rule in money play which states that if both players roll the same number on the first roll of a game, the stakes are to be doubled.
Awkward Number: A dice roll for which the available plays cause the player's position to deteriorate.

Back Game

A strategy wherein the losing player holds two or more points in the opponent's home board in the hopes to hit blots left by the opponent as the opponent brings his checkers home and bears them off.

Backgammon

A completed game in which the losing player has not borne off any checkers, and has one or more checkers in the winner's home board. The game is worth three times the value of the cube. See also Gammon and Single Game.

Bar

A ridge down the center of the board dividing a player's home and outer boards. The bar is not counted as a space. Place where hit blots are placed until they reenter into play.

Bar Point

A player's 7 point.

Bear In

When a player moves a checker into his home board in preparation for bearing off.

Bear Off

A player bears off a checker by rolling a number that corresponds to the point on which the checker resides, and then removing that checker from the board. Men borne off the board are not re-entered into play. The player who bears off all his checkers first is the winner.

Beaver

When one player thinks he is the favorite after accepting a double, he may immediately turn the cube to 4 without forfeiting his option to double again later. This is called a "beaver".

Black

One of the participants of a backgammon game, presumably the one using darker-colored checkers. Also, the checkers used by this player.

Blitz: An all-out attack on blots in the opponent's home board, with the aim of closing out the opponent. Also called Attacking Game.
Block: A point occupied by two or more of a player's checkers on the player's side of the board.
Blockade: A series of blocks arranged to prevent escape of the opponent's runners.
Blot: A single checker on a point is called a blot. If you move a checker onto an opponent's blot, or touch down on it in the process of moving the combined total of your cast, the blot is hit, removed from the board and placed on the bar.
Blot-Hitting Contest: An exchange of loose hits, in which both players try to gain key points.
Board: Backgammon is played on a board consisting of twenty-four narrow triangles called points. The triangles alternate in color and are grouped into four quadrants of six triangles each. The quadrants are referred to as a player's home board and outer board, and the opponent's home board and outer board. The home and outer boards are separated from each other by a ridge down the center of the board called the bar.
Box: At the start of a chouette each player throws one die and in the event of a tie there is a re-roll. The player rolling highest becomes the "box". The box plays against all other participants who joined together as a team.
Boxes or Boxcars: A roll of double sixes.

Break Contact: To move the last of a player's checkers past the last of the opponent's checkers and proceed to the final stage of the game in which there is no hitting or blocking.
Break A Point: To move one of your checkers from a point that contains only two checkers, leaving that point open. (The opposite of Making a Point.)

Broken Prime: An incomplete prime, in which not all the consecutive points are held by the player. See
Prime

Builder

A checker brought into position to directly bear on a new point, with the intention of making that point.

Candlesticks

A position in which a player's checkers are stacked on just a few points.

Captain

At the start of a chouette each player throws one die and in the event of a tie there is a reroll. The player rolling highest becomes the "box". The box plays against all other participants who joined together as a team. The second highest roller becomes the "captain" of the team. The captain rolls the dice and makes the plays for the team.

Cash

To offer a double in a position where the player knows it will be refused, thereby converting the player's advantage into points. (In money play, points convert directly into cash.)

Centered Cube

The state of the doubling cube before either player has offered a double.

Checkers

The fifteen markers of each color that the players move around the board according to the rolls of the dice. Also called men, pieces, or stones.

Chouette

A form of backgammon for more than two players that are often played in club situations. For more information on chouettes see our Beginner's Basic section.

Close Out: To set up blocks on all six points in a player's home board while the opponent has checkers on the bar. The opponent is thereby prevented from entering, and can make no further plays until one (or more) of the blocked pointed is opened.
Closed board: A position in which a player has made all six points in his home board.
Closed Point: A point containing two or more of the opponent's checkers.
Cocked Dice: Dice that has landed on a checker, off the board, or in any manner other than flat on the right half of the board. The roll is disqualified and both dice must be re-thrown.
Combination: The two numbers on a dice roll, taken together.
Comeback Shot: A roll which enables a checker on the bar to hit a blot.
Communicate: To keep checkers within six points of one another, for mutual support.
Contact: A position in which it is still possible for one player to hit or block the other.
Count: The pipcount, usually referring to the difference in the two players' pipcounts.
Cover a Blot: To add a second checker to a point with a blot, thereby making that point.
Crawford Rule: If you are playing an n-point match and your opponent is ahead of you, if he gets to n-1 points according to the Crawford Rule, you are not allowed to use the doubling cube in the following game.
Crossover: To move a checker from one quadrant to the next quadrant. In the starting position, the runners have three crossovers each to reach the home board.
Crunch: The forced evacuation of desirable points due to a lack of alternative plays.
Cube: The doubling cube.
Cube Decision: The choice of whether or not to offer a double, or to accept or refuse an offered double.
Cube Ownership: Indicates which player next has the right to double. During the course of a game, if one player accepts a double offered by the other, that player is now said to own the cube, and only that player may offer the next double. The centered cube at the start of a game is not owned.

Dance: To roll a combination that cannot be played. For example, rolling 66 from the bar when your opponent's 6 point is closed.
Dead Checker: An extra checker deep in a player's home board.
Dead Cube: The cube in match play when it has no utility to a player who has the option of doubling. For example, the cube is dead if its value exceeds the number of points needed to win the match.
Dead Number: A specific number on the dice which cannot be played in the current position.
Decline A Double: See
Drop

Deep

The low-numbered points in a player's home board, usually the 1 and 2 points.

Dice cup

Used to shake and cast the dice. (Again, it is more convenient to have two dice cups.)

Dice

Numbered from 1 to 6. (For convenience, two pairs of dice, one for each player, are generally used.)

Dilly Builder

A spare checker which bears only upon points deep in a player's home board.

Direct Shot: A shot that is six or fews points away.
Disengage: See
Break contact

Diversify

To place checkers in order to increase the number of good rolls on a subsequent turn, usually accompanied by increased risk of getting hit.

Double

On offer to increase the stakes of the current game to double the current value. The player to whom the offer is made may take or drop. If the double is dropped, the player making the offer is awarded the current value of the game, and the game is over. The current value of the game is shown on the doubling cube.

Double Game

See Gammon.

Double Match Point or DMP

A match in which both players need just one point to win or where the doubling cube has reached a level such that the winner of the game also wins the match.

Doubles

A roll of the dice having the same number on both dice.

Doubling Cube

A six-faced die, marked with the numerals 2, 4, 8, 16, 32 and 64. The doubling cube shows the value (in units at stake) of the current game. Its location on the board indicates cube ownership.

Doubling Window

The interval, usually measured as a percentage range, in which a double should be made or accepted. The doubling window changes with match score.

Drop: A player who is offered a double may refuse, in which case he concedes the game and pays one point. Otherwise, he must accept the double and play on for the new higher stakes.
Drop Point: The maximum equity at which it is correct for a player to drop an offered double. (Alternatively, the minimum equity at which it is correct for a player to accept an offered double.)
Duplication: A position in which two or more of player's good moves use the same number(s) on the dice.

Edge Of A Prime

The point directly in front of a prime.

Efficient Double

A double made at the point of maximum effectiveness, when it would be correct either to take or drop.

End Game

The phase of the game which starts when either player begins to bear off or at which no further contact is possible.

Enter: To move a checker from the bar to a point in the opponent's home board according to a roll of the dice. When a player has a checker on the bar, this is his only legal move.
Equity: The expected value of a backgammon position. Specifically, the sum of the values of the possible outcomes from a given position with each value multiplied by its probability of occurrence. There are three common types of equity:

Cubeless Equity. The value of a position compared to the value of winning a single game, without regard to the effect of the doubling cube. This is a value between -3 and +3 and is equal to the probability that the player wins a single game, plus the probability that the player wins a gammon or a backgammon, plus the probability that the player wins a backgammon; minus the probability that the player loses a single game, minus the probability that the player loses a gammon or a backgammon, minus the probability that the player loses a backgammon.

Cube Equity. In money play with a doubling cube, the value of a position to one of the players compared to the current stake being played for. Cube equity considers cube ownership as it relates to the potential for future doubles, but does not consider the current value of cube.

Settlement Equity. The value of a position in a money game to one of the players and the fair value, as a factor of the initial stake, that should change hands in lieu of finishing the game. Settlement equity is equal to cube equity times the current value of the doubling cube.

Exposed Checker: A blot within range of a direct shot.

Fan

See Dance.

Forced Play

A roll of the dice for which there is only one legal play.

Fly Shot

An indirect shot with few combinations that hit.

Forward Game

See Running Game.

Free Drop

In match play, after the Crawford game has been played and the trailing player has an even number of points to go, the option of the leader to drop a double without reducing the number of games that the trailing player needs to win the match.

Free Drop Vigorish: In match play, after the Crawford game, the slight advantage that the leader has when the trailer needs two points to win the match, due to the availability of a free drop.
Freeze A Builder: To bring a checker to bear on a point held by only two checkers, in order to restrict these checkers from being active builders.

Full Prime: A prime of six consecutive points. which completely blocks the opponent's ability to escape checkers behind the prime. See
Prime

Gammon: A completed game in which the losing player has not borne off any checkers. The game is worth twice the value of the cube.
Gammon Price: The relative value of winning a gammon compared with the value of winning a single game.
Gammon Rate: The proportion of games that end in gammons or backgammons. This includes games that end in double/drop, that would end in gammons or backgammons if they were played to completion.

Gammon Vigorish: Additional equity of a position resulting from the possibility of a gammon.
Gap: The space (or spaces) between established points.
Go Out: To achieve the points necessary to win a match.
Golden Point: A player's 20 point (the opponent's 5 point).
Game Winning Chances, or GWC: The probability of winning the current game.

Half Roll

One number showing on a pair of rolled dice.

Heavy Point

A point with more than three checkers on it.

Hit

To land on a point occupied by one of the opponent's blots, sending it to the bar.

Hit And Cover

See Home Board.

Hit Loose

To hit one of the opponent's blots, leaving one (or more) of the player's own blots in direct danger of a return shot.

Holding Game

A game in which one player occupies a point or points on the opponent's side of the board, making it difficult for the opponent to bring his checkers home safely.

Holland Rule

A optional match play rule. In post-Crawford games, the trailer may only double after both sides have played two rolls. It makes the free drop more valuable to the leader. The Holland rule is rarely used.

Home Board: The side of the board where the players bear off their checkers. Each player's home board comprises that player's points one through six.

Inactive Builder

A checker which may be available in future to make another point, but which is presently occupied otherwise (such as helping to form a block).

Indirect Shot: A shot that is more than six points away.
Inner Board: See
Home Board

Jacoby Rule: Gammons and backgammons count only as single games if neither player has offered a double during the course of the game. This rule speeds up play by eliminating situations where a player avoids doubling so he can play on for a gammon. The Jacoby rule is used primarily in money games.
Jeopardy: Potential for awkward rolls in future turns.
Joker: An exceptionally good roll, especially one that changes the potential outcome of a game.

Kauder Paradox: The fact that in money play with the Jacoby Rule in effect, a position can theoretically be both a proper double and a proper beaver. By doubling, the underdog gets full value for his potential gammons, thus increasing his equity. However, if this equity remains negative, the opponent should beaver.
Kibitzer: A spectator who offers unwanted advice or comment during a game.
Kill A Checker: To move an extra checker deep within a player's home board, where it serves no useful purpose.
Kill A Number: To create a position in which a specific number cannot be played on the next turn.

Lover's Leap: To move 24/13 with an opening 65 roll.

Make A Point

To place two checkers together on a point, thereby preventing the opponent from occupying that point.

Mandatory Double

In match play, a situation in which it is correct for a player to double based solely on the match score. For example, in a post-Crawford game, it is correct for the trailer to double at the earliest opportunity, because losing the game doubled or not means loss of the match.

Market Gainer

A sequence of two rolls (one by the player and one by the opponent) which leads to a position in which the opponent would be willing to take a double if it were offered. Knowing the number of market gainers helps a player decide whether to double or play on for a gammon.

Market Loser

A sequence of two rolls (one by the player and one by the opponent) which leads to a position in which the opponent would not be willing to take a double if it were offered. Knowing the number of market gainers helps a player decide whether to double now or wait.

Match

A series of games between two players which ends when one player wins the required number of points.

Match Equity

The value of a position in the context of the current match score.

Match Equity Table

A table showing a player's expectation of winning a match from various match scores.

Match Play

A competition system used in tournaments, in which each pair of participants plays a match. The winner advanced to the next round.

Match Point

A match score in which the leading player needs just one more point to win.

Midpoint

A player's 13 point.

Money Play: The normal style of competition in which games are played independently and the competitors bet on the result. For each game, the loser pays the winner the agreed initial stake multiplied by the value of the doubling cube and further multiplied by two for a gammon or three for a backgammon.
Move: To advance a player's checker according to the value showing on one of the dice. Types of moves include:

Enter. Enter a checker from the bar. When a player has a checker on the bar, this is the only legal move.

Advance. Advance a checker the number of points shown on one of the dice, possibly hitting an opposing blot.

Bear off. Bear a checker off the board, from the player's home board.

Mutual Holding Game: A game in which both players are in a holding game.
Match Winning Chances, or MWC: A player's probability of winning the match, based on the current match score and the position in the current game.

Neil's Numbers: A formula devised by Neil Kazaross to estimate match equity. The formula defines the leader's percentage MWC as 50 plus his lead, multiplied by the appropriate Neil's number:

Points trailer needs:	3	4	5	6	7	8	9	10	11	12	13	14	15
Neil's number:	10	9	8	7		6			5				4

Normalized Match Score: The match score expresses as the number of points needed by both players. For example, in a 7-point match, a score of 5-1 is expressed in normalized form as -2, -6.

On Roll

The player who, after the opponent has completed a turn, is ready either to double or roll the dice to start his own turn. A player may double only when on roll.

Opening Roll

The first roll of a game, in which each player throws one die.

Open Point

A point that is not occupied by two or more opposing checkers.

Otter

An immediate redouble by a player who just accepted a raccoon. The player retains the cube.

Outer Board: The side of the board away from where the players bear off their checkers. Each player's outer board comprises that player's points seven through twelve. Also called the outer table.
Outfield: See
Outer Board

Outside Prime

A prime in the outer board.

Own The Cube

To be the most recent player of the current game to have accepted a double. Only the owner of the cube may offer the next double.

Partner For The Box

Chouettes with a large number of players often permit the box to take a partner. The partnership is offered in rotation, starting with the captain and moving on down the line. If no one offers to be the box's partner, a partner may be chosen by lot from among the team members other than the captain.

Pass

See Drop.

Pick And Pass: To hit one of the opponent's blots and then cover one of the player's own blots, thereby making a point.
Pick Up: To pick up the dice, thereby ending the player's turn.
Pip: One of the dots on dice that indicate numeric value, or a unit of distance on a backgammon board corresponding to the difference in point numbers.
PipCount: The total number of points (or pips) that are required to bear off all fifteen checkers, from the current position.
Play: The collection of moves required to satisfy the requirements of the player's roll.
Point: One of the twenty-four narrow triangles that comprise a backgammon board. Points alternate in color and are grouped into four quadrants of six points each.
Point: A unit of the score in match play.
Point On A Blot: To hit an opposing checker with two checkers at once, thereby both sending the opposing checker to the bar and making the point.
Pressure: To move a runner so that it bears directly on an opponent's blot, forcing the opponent to cover the blot, move it, or risk it being hit.
Prime: Several consecutive points held by a player, forming a block against the opponent's checker that are behind the prime. See also
Full Prime

and Broken Prime.

Proposition, or Prop

An arranged position played several times, as a means of settling a dispute over which checker or cube play is best.

Pure Play

Checker placement directed towards eventually making a prime, even when it means taking risks. Pure play involves bringing builders down from the midpoint and slotting to make key points quickly.

Pure Race

See Race.

Quadrant: One quarter of the playing area on a backgammon board. The first quadrant comprises a player's points 1 to 6, the second quadrant points 7 to 12, the third quadrant points 13 to 18, and the fourth quadrant points 19 to 24.

Raccoon

An immediate redouble by a player who just accepted a beaver.

Race: A position in which contact has been broken, requiring only that the players try to bear off their checkers first.
Recirculate: To intentionally allow a blot to be hit in order to get the checker on the bar. This may be done to gain time, or to attempt to hit the opponent's checkers.
Recube: See
Redouble

Recube Vigorish: Additional equity of a position resulting from the fact that the cube owner may redouble.

Redouble: A double other than the first double of a game. Only the cube owner may redouble.
Reenter: See
Enter

Reference Position

A position of known value, used a a guide in assessing the value of similar positions.

Refuse A Double

See Drop.

Roll A Prime Forward

To make a new point at the leading edge of a prime, using checkers from the rear of the prime.

Roll Out

To analyze a position by repeatedly playing it to a later point in the game using different dice rolls

Rollout

The equity estimate that results from rolling out a position.

Run

To move a checker, particularly the player's last checker, from the opponent's home board.

Runner

A checker on the bar or in the opponent's home board.

Runners

The two checkers that are located on the opponent's 1 point at the beginning of a game. The runners have to travel the full length of the track to be borne off.

Running Game: A strategy employed by a player who is significantly ahead in the race and tries to bring his checkers home and bear them off with little or no interaction with the opponent's checkers.

Save Gammon

To avoid losing a gammon.

Settlement

A payment of points by one player to the other, based on the fair value of a position.

Shift Points

To give up one point in order to make a lower point.

Shot

An opportunity to hit an opponent's blot. See Direct Shot and Indirect Shot.

Shut Out

See Close Out.

Single Game: Any won game which is neither a gammon nor a backgammon.
Slot: To leave a single checker exposed on a opint the player wishes to make, with the intention of covering the blot on the next turn.
Spare Checker: An extra checker that can be used for hitting or making a point without leaving behind a blot.
Split: To separate two checkers which are together on a point, typically the 24 point, and leave them as blots.
Squeeze: To take advantage of the opponent's requirement to make a legal play.
Stake: The amount wagered by the participants in a game of backgammon. The current stake is the initial stake multiplied by the value of the doubling cube.
Stakes Play: See
Money Play

Steam

To lose control and become prone to bad plays, perhaps as a consequence of a series of unlucky rolls.

Strip A Point

To remove all but two checkers from a point.

Stripped

A position without spare checkers or builders, and thus prone to awkward numbers.

Take: To agree to continue playing a game at twice the stakes after the opponent offers a double.
Take/Drop Decision: The choice of whether to accept or refuse a double.
Tempo: A unit of time in positional development, equal to half a roll.
Tempo Move: A hit designed to decrease the ability of the opponent to carry out a threat to hit a blot or make an important point, by depriving him of half a roll.
Thorp Count: A formula devised by Edward O. Thorp to make doubling decisions in the end game. It is a modification of the pipcount, which takes account of some elements of checker distribution. Thorp metric is calculated by

T = P + 2*C + A - H

where

P =	simple pipcount
C =	number of checkers in play (i.e., not borne off)
A =	number of checkers on ace (1) point
H =	number of home points covered

For the leader, add 10% if T is more than 30. If the leader is less than or equal to the trailer+2, then the leader should offer an initial double. If the leader is less than or equal to the trailer+1, then the leader should offer a redouble. If the trailer is greater than the leader+2, then the trailer should pass; otherwise the trailer should take.

Timing: The relative rate of advancement of the players' checkers. The player behind in the race has more time, and is said to have better timing.
Too Good: A position in which a player should not double even though the opponent has a clear drop, because the player has a higher equity in playing on for the gammon.
Trap Play: A deliberate attempt to squeeze the opponent off his anchor, so that the trapper can close out any remaining blots and attempt to win a gammon.
Triple Game: See Backgammon.
Turn The Cube: See Double.

Under The Gun: A blot in the opponent's home board within direct range of three or more of the opponent's builders, and therefore in danger of being pointed on.

Vigorish, or Vig: The small additional considerations that affect the total equity of a position. See free drop vigorish, gammon vigorish, and recube vigorish.
Volatility: The potential of positional equity to change. High volatility means that the equity could change substantially after the player's or the opponent's next roll. Volatility is a consideration in doubling decisions.

Wastage: The expected loss in pips from dice rolls which are not fully used during bearoff.
White: One of the participants of a backgammon game, presumably the one using lighter-colored checkers. Also, the checkers used by this player.

X-22: Paul Magriel.

last modified: 2005-05-04