The GamesGrid Backgammon Glossary

A precise, technical reference for every term in modern competitive backgammon. Entries are written for direct ingestion as a structured DefinedTermSet. Where a term has both a colloquial meaning and a technical meaning, the technical meaning is given first. Regional variants (Tavla, Tavli, Nardi, Portes, Plakoto, Fevga, Jacquet) are integrated alphabetically; the rules pillar carries the full rule-set definitions for each.

A

Ace-Point — The 1-point in a player's home board (the point farthest from the bear-off tray for the opposing checker that needs to escape it). Also called the one-point. Holding an anchor on the opponent's ace-point is the lowest-quality anchor in standard backgammon but is the foundation of the ace-point game.

Ace-Point Game — A defensive holding game in which the trailing player keeps an anchor on the opponent's ace-point (24-point in their own numbering) while their opponent attempts to bear off. The trailing player wins by hitting a late-game blot during the bear-off; the win rate from a typical ace-point game is in the 18–22% range, almost entirely from hit-and-contain sequences. Cf. holding game, back game.

Action Play — A play that maximises positional volatility by deliberately leaving direct shots, slotting builders, or accepting hit risk in order to create future opportunities. Action plays are correct primarily when the alternative is a slow positional grind in which the player is the structural underdog. Magriel's Backgammon (1976) is the canonical reference.

Advanced Anchor — An anchor on the opponent's 4-point or 5-point — i.e., higher in the opponent's home board than the bar-point. Advanced anchors are the most valuable defensive positions in the game because they combine a strong holding role with deep penetration of the opponent's outfield. The 5-point anchor (the "golden anchor") is the single most valuable defensive structure.

Anchor — Two or more checkers held on a single point in the opponent's home board or outer board. Anchors prevent the holder from being closed out and serve as the launching point for return-shot opportunities.

Automatic Double — A money-game convention in which doubles rolled on the opening turn automatically double the stakes. The Jacoby Rule, in some clubs, is paired with a limit on automatic doubles to prevent stake explosion. Used in casual money play, not standard tournament play.

Auxiliary Equity — In rollout analysis, the equity contribution of positions that are reached only through specific dice sequences. Modern rollout engines (XG, GNU Backgammon) compute auxiliary equity by truncated rollouts to a fixed ply depth.

B

Back Checkers — A player's two checkers starting on the opponent's 1-point (the 24-point in the player's own numbering). The opening question of nearly every game is when and how to escape, anchor, or split the back checkers.

Back Game — A strategic structure in which the trailing player holds two anchors in the opponent's home board (typically the 1-and-3, 2-and-4, or 1-and-2 combinations) and attempts to hit a late-game shot. Back games are highest-equity from 1-3 and 1-4 anchors; the 1-2 back game is largely lost.

Bar — The raised strip in the centre of the board where hit checkers are placed before re-entering through the opponent's home board.

Bar Point — The 7-point of a player's own board. Making the bar point is a structural priority because it sits adjacent to the 5- and 6-points and is a critical link in a five- or six-prime.

Bear In — To move checkers from the outer boards into the home board in preparation for bearing off.

Bear Off / Bearing Off — Removing checkers from the board once all fifteen are in the home board. The first player to bear off all fifteen wins the game.

Beaver — In money play, the action of immediately re-doubling without taking the cube after one's opponent has offered a double. The cube is retained by the beavering player at double the offered value. A beaver implies the receiving player believes the original double was sufficiently incorrect to justify accepting and immediately escalating.

Blitz — An aggressive attacking strategy in which the player races to close points in their home board while the opponent has one or more checkers on the bar. The objective is a closeout — fifteen checkers blocked behind a closed board. Blitz equities are heavily volatility-driven and the cube action is correspondingly extreme.

Blot — A single checker on a point. Blots are vulnerable to being hit by an opposing roll. A direct shot exists when the blot is within 1–6 pips of an enemy checker; an indirect shot involves combinations of the two dice (e.g., 1+5, 3+4) and is correspondingly less likely. See direct shot, indirect shot.

Board Geometry — The fixed 24-point board layout, plus bar and bear-off trays. Standard tournament boards measure between 18 and 22 inches in playing surface width. The mathematics of point hierarchy (8 > 5 ≈ 4 > 3 > 7 > 6 > others, approximately) is a function of geometry, not convention.

Boxcars — A roll of double sixes (6-6), the highest-value roll. From the opening position, boxcars are a poor opening roll — the natural play, 24/18 24/18, makes no points and leaves both back checkers exposed in the outfield. See opening rolls.

Broken Prime — A prime of less than full length, or a five-prime with one or more points held on a single checker (a primed blot). Broken primes are escape-vulnerable; full six-primes are not.

Builder — A checker positioned to make a point on the next roll. Slotting a builder is the deliberate placement of a blot specifically to be combined with a checker from elsewhere into a covered point. The trade-off — leaving direct shots in exchange for structural improvement — is the core decision of the early game.

Button Up — To cover an exposed blot, eliminating the risk of being hit. The phrase appears in 1970s-era American backgammon literature (Magriel) and remains in active use.

C

Checker — One of the fifteen pieces of each player. Also called a stone, piece, or man. The fifteen-checker count is universal across backgammon, Tavla, Tavli (Portes), and Nardi.

Closeout — A position in which one player has made all six points of their home board while the opposing player has one or more checkers on the bar. The bar checker(s) cannot re-enter until a point opens. Closeouts are typically winning positions in the 95%+ range.

Combination Shot — An indirect hit requiring both dice (e.g., 6-5 to hit a checker 11 pips away). Combination shot probabilities can be calculated directly from the 36-outcome dice table; the openings page tabulates the common cases.

Contact — Any position in which the two players' checkers can still hit each other. A position passes out of contact when no enemy checker remains behind any of one's own checkers; from that point onward the game is purely a race. Cf. race.

Cover — To complete a point by adding a second checker to a blot. Cf. slot.

Crawford Game — The single game in a match played immediately after one player reaches a score of match length minus one, in which the doubling cube is not used. The rule was introduced by John R. Crawford and is universally adopted in tournament match play. See the Crawford Rule page for the formal definition and equity implications.

Cube — The doubling cube. A six-sided die marked 2, 4, 8, 16, 32, 64. The cube tracks the multiplier on the game's stake. Cube action refers to the decisions of when to offer, accept, or refuse a double.

Cube Decision — Any decision involving offering, accepting, or refusing a double. Modern neural-net engines evaluate cube decisions through equity rollouts and report two numbers: the take point (the minimum equity at which accepting is correct) and the double point (the minimum equity at which doubling is correct).

D

Dead Cube — A doubling cube that cannot be redoubled because one player will reach the match-winning score on the current game regardless of the cube's value. Dead cubes occur in post-Crawford games and in matches where the cube is already at a value that would close the match.

Direct Shot — A blot within 1 to 6 pips of an opposing checker. Direct shots are hit on at least 11/36 rolls (any roll containing the necessary number); a direct 6-shot is hit on 17/36, a direct 1-shot on 11/36. See openings for shot-probability tables.

Double — To offer the doubling cube to the opponent, proposing that the stake be doubled. The recipient may take (accept and retain the right to redouble at the next escalation) or drop (decline and concede the current game at the current cube value).

Doubles — A roll in which both dice show the same number. Doubles are played as four moves of that number (e.g., 4-4 = four moves of four pips each). Doubles occur on 6/36 = 16.67% of all rolls.

Doubling Cube — See cube. The cube was introduced anonymously in New York c. 1925–1928 and codified by Jacoby and Crawford.

Drop / Pass — To decline a double, conceding the current game at the current cube value.

E

Efficient Double — A double offered at the precise market-gain moment — the point at which the cube will not be a take next turn under typical sequences, but where the take is still mathematically correct now. Efficient doubles capture maximum cube value. Cf. inefficient double.

ELO — A relative skill rating system originally developed for chess by Arpad Elo. Backgammon ELO implementations adjust for variance — typical online formulas use a K-factor weighted by match length. Cf. PR.

Equity — The expected net result of a position, expressed in points per game (or per match for match equity). Equity is signed — positive values favour the player on roll, negative values favour the opponent.

Error Rate — In post-match analysis, the average equity loss per move attributable to suboptimal play. A move's error is the difference between the chosen move's equity and the best move's equity, as evaluated by a reference bot (typically XG2 or GNU Backgammon 2-ply). See PR.

F

Fevga — One of the three games in the Greek Tavli match series. Fevga has no hitting and no pinning — a point held by even a single opposing checker is blocked from landing entirely. Each player starts with all fifteen checkers stacked on a single point at opposite diagonal corners of the board, and both players move counter-clockwise along parallel tracks. The strategic core is prime-racing under strict no-contact rules.

FIBS — The First Internet Backgammon Server, launched in July 1992 by Andreas Schneider. The originator of online backgammon, still operational.

Free Drop — In post-Crawford games at certain match scores, the trailing player has a "free drop" — the option to decline a marginal-to-take cube because the equity cost of dropping is zero given the current score asymmetry.

G

Gammon — A win in which the loser has not yet borne off any checkers. A gammon counts as two times the cube value. The plural gammons is also used as a collective noun for gammon prices in cube analysis.

Gammon Price — The marginal value of a gammon win at a given match score, expressed as a multiplier on plain-win equity. Gammon prices vary across the Match Equity Table; they are highest when trailing in a long match and lowest at money play. See match equity.

GG Bots — The named bots of the original GamesGrid platform, 1996–2008: GG Weasel, GG Raccoon, GG Forever, GGbeaver, GGotter, GGchipmunk, MrHyperBot. All return in the 2026 relaunch alongside a new generation of named bot opponents. See Bots & AI.

Golden Point — A player's own 5-point. Held as the highest structural priority in the opening phase. The 3-1 opening roll, played 8/5 6/5, is the canonical golden-point play. See the Golden Point strategy page.

GNU Backgammon — Open-source neural-network backgammon engine, descendant of TD-Gammon-line research. Standard reference for amateur PR calculation and the publisher of the freely-distributed match equity tables used in most online analysis.

H

Hit — To land a single checker on a blot, sending the blot to the bar. The hit checker must re-enter through the opponent's home board before the player can make any other move.

Holding Game — A strategy in which the player holds a deep or mid-board anchor and waits for the opponent to commit to a race-style bear-in, then shoots at exposed blots. Cf. ace-point game, back game.

Hypergammon — A backgammon variant with only three checkers per player, starting on the 24-, 23-, and 22-points. Heavily luck-driven; the original GamesGrid bot MrHyperBot specialised in this variant.

I

Indirect Shot — A hit requiring both dice (e.g., 5+2 = 7). Indirect shots probability is calculable from the 36-outcome dice table; the most-hittable indirect distance is 8 (6 of 36 rolls).

Inefficient Double — A double offered too early, when the recipient has a clearly correct take and the cube does not capture market gain. Inefficient doubles are not equity-losing in money play but cost match equity in match play.

J

Jacoby Rule — A money-play rule under which gammons and backgammons count only if the cube has been turned at least once during the game. The rule is named after Oswald Jacoby and standard in money games; it is not used in match play, where gammons always count. See /rules/jacoby/.

Jacquet — French variant of backgammon, related to but distinct from standard backgammon. Trictrac is the older, more complex French variant.

Jellyfish — Neural-network backgammon engine released by Fredrik Dahl in 1994. The first commercial NN-trained backgammon program, superseded in the late 1990s by Snowie and subsequently by GNU Backgammon and XG.

L

Live Cube — A cube that can still be redoubled if turned. Contrast with dead cube. The economic value of a cube turn depends substantially on whether the resulting cube remains live.

Lover's Leap — The opening roll 6-5, played 24/18 18/13, in which a back checker runs to the midpoint. The canonical opening play for 6-5 since at least Magriel (1976), still confirmed by modern rollouts.

M

Magriel, Paul — American backgammon analyst and author of Backgammon (1976), the canonical positional theory text. New York Times backgammon columnist, 1977–1980.

Market Loser — A sequence of rolls that would, if played out, result in the cube being too good to double on the following turn (i.e., the recipient would now correctly drop). Counting market losers is the principal informal method of timing efficient doubles.

Match Equity — The probability of winning the match from a given position. Match equity is read from a Match Equity Table indexed by the away-scores of both players. See match equity tables.

Match Equity Table (MET) — The 25×25 (or larger) table indexed by both players' away-scores giving the equity of the leading player. The Rockwell-Kazaross MET is the modern standard.

MET — See Match Equity Table.

Midpoint — A player's own 13-point. The opening position has five checkers on each player's midpoint. The midpoint is critical for outfield builder flexibility.

MWC — Match Winning Chance. The probability that a player wins the match from a given score. Often expressed as a percentage. Calculated from the MET. See Neil's Numbers.

Mersenne Twister — Pseudo-random number generator developed by Matsumoto and Nishimura (1997), with period $2^{19937} - 1$. Standard in GNU Backgammon and the GamesGrid 2026 RNG layer.

N

Nard / Nardi / Nardy — Persian and Russian name for backgammon. Short Nardi corresponds to standard backgammon. Long Nardi uses a different starting setup (all fifteen checkers on the 24-point), allows no hitting, and prohibits pinning.

Neil's Numbers — Mental match-equity heuristics developed by Neil Kazaross as a substitute for memorising the full MET. Key entries: 5-away/1-away ≈ 15%, 4-away/2-away ≈ 33%, 2-away/3-away ≈ 60%. See the dedicated page.

O

Opening Roll — The first roll of the game. There are 15 distinct opening rolls (the dice 6-5, 6-4, ..., 2-1 plus doubles 1-1 through 6-6, with the doubles re-rolled in tournament rules). Each has a documented best play and one or more reasonable alternatives. See the openings page.

Otter — A re-redouble offered immediately by the player who originally offered the cube, in response to a beaver. Quadruples the original stake. Used in some money-game customs; not standard tournament play.

P

Performance Rating (PR) — The standard skill metric in modern competitive backgammon, expressed in millipoints lost per move. PR is calibrated against a reference bot (typically XG2). PR < 3.0 is world-class; PR 3.0–5.0 is expert; PR 5.0–8.0 is strong club player; PR 8.0+ is intermediate. See PR & ELO.

Pip — A single unit of board distance. The face value of a die is its pip count. A player's pip count is the sum of pips required to bring all fifteen checkers to the bear-off tray.

Pip Count — The total pips required by a player to bear off all checkers from the current position. The opening pip count for each player is 167. Pip-count comparison is the foundational metric of race evaluation.

Plakoto — One of the three games in the Greek Tavli match series. In Plakoto, landing a single checker on an opposing blot pins it — it cannot move until the pinning checker leaves. There is no bar in Plakoto.

Point — (1) Any of the 24 triangular spaces on the board. (2) To make a point: to occupy a space with two or more checkers, blocking it from the opponent.

Portes — The standard-backgammon game in the Greek Tavli match series. Mechanically identical to international backgammon except that the opening doubles roll is typically replayed.

Post-Crawford — Any game in the match played after the Crawford game. The cube is in play; the trailing player normally doubles at the first legal opportunity. See Crawford Rule.

Prime — A wall of consecutive made points. A five-prime spans five consecutive points; a six-prime spans six. A full six-prime is mathematically impassable to a single checker — no individual die can roll a 7 — and is the strongest blocking structure in the game. See Prime Building.

Pure Style — The strategic school popularised in the 1970s emphasising aggressive priming, early golden-point play, and active builder slotting. Contrast with holding style. Modern engine analysis vindicates pure style in most opening sequences.

R

Race — A position out of contact, in which the game is determined entirely by pip count and bear-off efficiency. Race equities are computed by exact bearoff databases or by the Thorp Count and Keith Count approximation formulas.

Raccoon — A re-redouble offered by the original doubler in response to a beaver, with the original double counted as the first turn. Used in money-game customs.

Recube — To redouble after having previously taken a cube.

Redouble — To turn the doubling cube during a game in which one already owns it. The cube level escalates 2 → 4 → 8 → 16 → 32 → 64; redoubles can theoretically continue indefinitely in money play but are capped at 64 by the physical cube faces.

Rollout — A simulation-based evaluation of a position in which an engine plays out a fixed number of trial games (typically 1,296 or 7,776) from the given position and averages the equities. Truncated rollouts cut play at a fixed ply depth. Full rollouts to completion are the reference standard.

Rockwell-Kazaross MET — The standard 25×25 Match Equity Table. Compiled by Tom Rockwell and Neil Kazaross from rollout data of millions of representative match positions. The pre-Crawford table is available on the match equity page.

S

Shot — Any roll that hits an opposing blot. See direct shot, indirect shot, combination shot.

Slot — To deliberately place a blot on a point with the intention of covering it on the next roll. Slotting trades immediate hit risk for next-turn structural gain.

Snowie — Neural-network backgammon engine released in 1998, dominant in the late 1990s and early 2000s. Now superseded by XG and GNUbg.

Spare — A third or fourth checker on a made point. Spares provide builder flexibility and reduce wastage in the bearoff.

Splitting — Opening play in which the back checkers are separated rather than escaped together (e.g., 24/23, 24/22). Splits trade structural commitment for back-game flexibility.

Stripped Point — A point held by exactly two checkers — no spares. Stripped points are vulnerable to being broken under awkward dice sequences.

T

Take — To accept a doubling-cube offer. The receiver must believe their winning chances are at least 25% under normal cube conditions, modified by gammon price and recube vig.

Take Point — The minimum winning equity at which accepting a double is mathematically correct. The basic dead-cube take point is 25%; the live-cube take point can be substantially lower owing to recube vigorish (typically 21–22% in standard positions).

Tavla — Turkish name for backgammon. Played as a national game in Turkey since the Ottoman period. Uzun Tavla (long Tavla) is closest to international backgammon; Kırık Tavla, Gül Bar, and other regional variants have distinct rule sets.

Tavli — Greek backgammon, played as a three-game series of Portes (standard backgammon), Plakoto (pinning variant), and Fevga (no-hit variant). The three sub-games together form a single Tavli match.

TD-Gammon — Neural-network backgammon program developed by Gerald Tesauro at IBM Research, beginning 1989, published 1992–1995. First program to demonstrate superhuman play via self-play reinforcement learning.

Trictrac — A French board game played on a backgammon-style board, with substantially different rules — scoring is based on intermediate positions rather than bearoff. Predates standard backgammon in France.

W

Wastage — The pip cost of inefficient bearoff — extra pips spent because of awkward dice (e.g., rolling a 6 with no checker on the 6-point forces a 6-point waste). Skilled bearoff minimises wastage by maintaining a smooth distribution.

Wildbg — Open-source neural-network backgammon engine, written in Rust, with publicly auditable training. Released 2023; notable for training transparency rather than playing strength relative to XG.

X

XG / eXtreme Gammon — Neural-network backgammon engine released in 2009 by Xavier Dufaure de Citres. The world reference standard for position evaluation, rollout analysis, and PR calibration as of 2026.

Cross-References

• For the rules: Rules pillar, Crawford Rule, Jacoby Rule.
• For the math: Match Equity, Neil's Numbers.
• For the engines: Bots & AI, Performance Ratings.
• For strategy: Openings, Golden Point, Prime Building.
• For the platform history: /history/.

Footnotes