my personal definitions marked "(Dan)" - last updated 01/16/2013
Acquiesce (Dan) - To quickly make a losing move capitulating when there is adequate time on the clock and it was possible that more thought would produce a move that could save the game.
Action Chess A game where each player has 30 minutes to make all his moves.
Activity (Dan) The positive actions a piece (or pieces) can do in a given position
Actual Mobility See Mobility
Advance Entries The players who Pre-registered (See "registration") for an event. Usually posted before an event.
Advantage of the two bishops - See "Bishop Pair"
Algebraic Notation A method for writing moves down by using the names of the pieces and the ranks and files. Replaced older Descriptive Notation (“P-K4" is now "e4") about 1970.
Amateur In chess, a non-master. At the US Amateur, masters cannot play. At the US Amateur Team tournaments, the team has to average below master rating. Note: in chess, amateurs can win money, sometimes quite a bit at tournaments like the World Open.
Analysis The part of the thought process where you generate the move tree, e.g. "If I go there, what would he do?"
Annotation To not only show the moves of a game, but provide additional text and moves showing more detail of what happened - or could have happened.
Artificially Isolated A pawn that has at least one pawn on a neighboring file, but neighboring pawns are unable to guard or be guarded easily (usually one is stuck on a rank where it cannot support)
Attack When you move a piece to a square where you could capture an opponent’s piece NEXT move. Also, when you have the initiative and can put pressure on specific squares, e.g. I am attacking the kingside.
Back Rank The rank where a player sets up his major pieces (1st for White; 8th for Black)
Back-Rank Mate A checkmate on the 1st or 8th rank with a Rook or Queen where that piece also covers all the escape squares on that rank. Can also be made on the a or h-files
Backward Pawn One that cannot safely advance, taking into account only the pawns on both sides. A pawn that is fixed (cannot move because another pawn is directly in front, i.e. a "ram") is, by definition not backward. Nor is the rearmost pawn in a pawn chain usually a backward pawn.
Battery Lining up two pieces that move similarly, like a Queen and Rook or Queen and Bishop.
Bishop Pair (The Advantage of...) This is when one player has two Bishops and the other does not.
Blitz Fast chess. Many blitz games are 5 minutes per player for the entire game. Chess played at a fast enough time control where good moves are generally less important than the time remaining.
Board Vision (Dan) - The ability to look at a chess board and quickly see what all the pieces are doing (statically). For example, seeing that a bishop on a1 is attacking h8.
Book Besides the kind with a spine, a “book” move is one that a player has learned to play in a particular position in the opening (from a “book” or other media) without the need to “calculate”. All the book moves in a certain opening before a major deviation is a tabiya.
Bookup A chess program that enables one to store moves in a tree from the opening position, train, etc. Now "Chess Opening Wizard"
Blindfold chess A game played where one or both parties are not permitted to look at the board, but must visualize the entire game as they are dictated the opponent's moves.
Blunder A bad move; primarily a move that turns a win into a loss or draw, or a draw into a loss. Note that ANY bad mistake is a blunder - not just a counting mistake, or falling into another tactic.
Botvinnik's Rule A time management principle that says in "normal" openings you want to use roughly 20% of your time for your first 15 moves
Break move A pawn move attacking an opponent's fixed pawn (thus forcing the possible "break up" of his pawn structure)
Bughouse A variant of chess with two players on each side – a player gets the pieces his partner captures and may place one on an empty square in lieu of a "regular" move.
Bye What you get as a score when you can’t play a round, but are still continuing to play in the tournament. Byes don’t count for ratings, but can be either 0 points, ½ point, or 1 point (the latter in case you want to play, but are the odd person available). See also "forfeit"
Calculation The part of analysis involving forced sequences.
Candidate (move) A move under consideration (during the thought process). Some specific types of Candidates
1) King of the Hill - the best candidate found so far.
2) Initial Candidate (Dan) - any move which does something positive
3) Final Candidate (Dan) - a candidate which is safe (cannot be easily defeated by a forcing move)
Capture (or Take) To remove a piece from the board via a legal move - not kill or eat (although other languages use these terms)
Castle To move your unmoved King 2 squares toward an unmoved Rook and to move the Rook on the other side of the King; not another name for a rook.
Check An attack on the King. You do not have to announce “check”.
Checks, Captures, and Threats - (Dan ) The three types of forcing moves. Note that threats to checkmate are more forcing than captures and sometimes even more than checks.
Checkmate An attack on the King where there is no way for your opponent to finish his turn and not longer have the King attacked.
ChessBase An advanced chess database program that enables one to store and search games, etc.
Chess.com The largest online chess website with almost 6,000,000 members. I have a show "Q&A with Coach Heisman" on Chess.com TV every 2 weeks and we have a "Dan Heisman Learning Center" as a group there.
Chess Maze A type of board vision problem where you move one White piece multiple times in a row to capture the Black king. There are restrictions where it can move, e.g. can't move to squares guarded by Black pieces
Chessville An online chess community with information, store, forum, etc.
Closed File A file with pawns of both sides
Closed Position A position without any open or semi-open files. If instead/addition some pawns are immobile due to opponent pawns, see "Fixed Pawn Structure"
CM Candidate Master - A FIDE title for those with FIDE ratings between 2200-2299 (Dan is a CM).
Complex 1) Complicated (not necessarily chess), also in chess: "Sharp"
2) A set of squares of the same color in one part of the board. e.g. "White has a weak dark square complex on the queenside."
Coordination The ability for various pieces to work together harmoniously to achieve a goal.
Counting (Dan) Seeing if pieces are safe from capturing sequences; checking to see if any forced sequence of captures on any square or squares will gain or lose material.
Critical move A move in a position where the best move(s) are enough better than the second best to make a difference (win to draw or loss; draw to loss; easy win to difficult win). Critical moves often include complicated decisions, trading pieces, or inflexible plans which cannot be changed. One which should be played carefully and slowly.
Criticality Assessment The ability to differentiate the criticality of a move.
Crosstable A chart showing how each player did in each round.
CTD Club Tournament Director
Dan's Metric (Dan) The move number in a game where you first can state that all your non-pawns (except the King) are developed (active).
Deep Blue A famous IBM chess playing program, hardware based, which played Garry Kasparov in two world-famous matches in 1996 and 1997, winning the second.
Descriptive Notation An old chess notation used primarily in English texts including moves such as "P-K4" or "NxB"
Desperado A piece that is going to be captured anyway so it may be able to "sacrifice" itself at the highest cost.
Discovered Attack An attack by a piece that was opened up via another piece’s move. (also "Discovery")
Discovered Check A discovered attack where the discovered piece also makes a check.
Discovery See Discovered Attack
Domination 1) When a knight or bishop dominates the other, by guarding all it's potential moves
2) (Dan) when a move, compared to another, has all pros and no cons
Double Attack An attack on two (or more) pieces by a single move
Double check A discovered check where both the discovering and discovered piece both deliver check. In that case, the opposing king must move.
Double Whammy A type of problem where you make two pieces moves in a row for White and leave Black in a legal checkmate. The first move may not be check. See Jeff Coakley's Winning Chess Puzzles for Kids, Vol II
Doubled Pawns Two pawns of the same color on the same file as a result of a capture
Doubled Rooks Two Rooks forming a battery on a rank or file.
Draw NOT “tie” - Any game that ends without either player winning, e.g. Stalemate, Lack of Mating Material, 50-Move Rule, etc.
En Passant Capturing a pawn that moved 2 spaces with a pawn that could have captured it if it had only moved 1 space, on the next turn only.
En Prise "In take" - able to be captured for free. A piece is en prise if it can be captured but is not guarded. Pronounced "aan-preez"
Endgame The part of the game where the King should come out and fight (with fewer pieces left on the board).
Evaluation The part of the thought process performed at analysis nodes (moves that generate positions) which asks Who stands better, how much, and why?
Exchange (the) Trading a Bishop or Knight for a Rook is winning the Exchange. Losing a Rook for a Bishop or Knight is losing the Exchange. NOT the same as trading pieces.
Expert Someone with a US Chess Federation rating between 2000 and 2199
Fianchetto To develop a Bishop on a long diagonal (b2 or g2 for White; b7 or g7 for Black).
FIDE Master (FM) Someone with the lowest International Chess Title
Fifty-Move Rule A type of draw where both players make 50 moves consecutively without either player advancing a pawn or making a capture.
File The rows of a chessboard going up and down, lettered a-h (lower case), with “a” always on White’s left (and Black’s right)
Fish A weak player; see patzer.
Five Minute/Blitz A game where each player has five minutes to make all his moves. Blitz can also be any fast game.
Fixed Pawn Structure A game where multiple pawns cannot move, primarily because an opponent pawn is directly in front (Kmoch: "Ram"), e.g. White d4/e5 vs. Black d5/e6
Flag The part of an analog clock that rises when the minute hand nears the hour and falls at the hour. To "flag" someone is to call them on a time forfeit.
Flexibility The capability of a piece or entire army to do multiple good things. A lack of flexibility is rigid and generally very bad.
Floobly (Dan) Something which allows a player to suddenly win/draw despite his opponent's easily won position, e.g. overlooking a checkmate, stalemate, winning on time.
Fool’s Mate A 2-move mate. Anything similar to 1. f3? e5 2. g4?? Qh4#
Forcing moves Checks, captures, and threats or, more specifically, checks, threats of mate, captures, and other threats.
Forfeit Has 2 Definitions, depending upon context
1) When you are expected to play, but don’t show up for a game (which is therefore not rated), or
2) When someone loses on time, a “time forfeit” (which is rated like any other loss)
Fork A double attack, usually by a Knight or Pawn (thus forming a pattern like a “fork” in the road).
Fritz A popular and very strong chess engine.
Gambit Sacrificing material (usually a pawn) in the opening for a lead in development, open lines, and/or attacking chances
Global Mobility See Mobility.
Grandmaster (GM) Someone with the highest International Chess Title
Hand-Waving (Dan) - When you erroneously use general principles to decide upon a move in an analytical position when only careful analysis is required instead.
Helpmate A type of problem where Black moves first and cooperates with White to checkmate Black in a fixed number of moves.
Hole A weak square on the opponent's side of the board.
Hope Chess (Dan) When you make a move without considering whether a possible opponent reply of a check, capture, or threat can be met.
My use of Hope Chess was NOT supposed to cover these other "Hope" possibilities:
1) When you make a threat and hope your opponent does not see it, nor
2) When you make a bad move on purpose but hope your opponent makes a worse one
3) You make a unanalyzed move quickly and hope the move/idea/maneuver works anyway
Horse A beginner's word for a knight (worse: "He took my horsey!")
Houdini The highest rated computer program in the world 2011-2012
Hydra A multiprocessor, hardware-based chess program. Very strong. Successor to Deep Blue. Now defunct
Increment Time (in seconds) added to your clock for each move. For example, in the Team4545 League the time control is 45 45 so you get 45 minutes for the game plus 45 seconds added for each move. As opposed to time-delay
Illegal Move A move that either a) Moves a piece in an illegal manner, or 2) Results in an illegal position, such as leaving the moving player's king in check at the end of the move.
Initiative When your opponent is constantly responding to your forcing moves (checks, captures, and threats)
Insufficient Losing Chances - A USCF draw rule where a player with less than two minutes remaining on an analog clock may claim a draw if he thinks he is clearly not losing but is in danger of losing on time. The TD has several options on how to rule, depending on the position. A common ruling is to exchange the analog clock for a time delay clock, but giving the claiming player half of his remaining time.
International Master (IM) - Someone with the "intermediate" International Chess Title
Internet Chess Club (ICC) - a leading chess server; owner of Chess.FM and another online chess server, World Chess Live (WCL)
Isolated Pawns Pawns that have no other pawns of the same color on adjacent files.
J'Adoube French. Means "I adjust" - used before touching a poorly placed piece to place it on the center of a square, or to fix a piece accidentally knocked over.
King of the Hill The best candidate move you have found so far. The move which creates the position for which you are trying to find another move which creates a better one.
Knight not Horse – the piece that moves like an “L”
Lasker's Rule If you see a good move, look for a better one (because you are trying to find the best move you can in a reasonable amount of time).
LPDO Loose Pieces Drop Off (Nunn's Dictum)
LTD Local Tournament Director
Luft German for "air" - a square where the king can escape to prevent back-rank mate, created by moving a pawn.
Master Someone with a US Chess Federation rating between 2200 and 2399 is a national master (NM). There are higher levels of master, both national and international.
Match A series of games with a purpose (as opposed to "game" which is a single contest between two players):
1) A set of games between two players, e.g. the "World Championship Match"
2) A set of games between two chess teams; e.g. "Our club will play a match against their club"
Mate Short for "Checkmate"
Material Piece value - when you win a pawn, a piece, the Exchange, you are winning "material" On the average a Knight and Bishop are worth 3.25 pawns, a Rook 5 pawns, a Queen 9.75 pawns, and the King has a fighting value of about 4 pawns. Give yourself a bonus of 0.5 pawns if you have the advantage of the Bishop pair.
Mating Material Enough material to checkmate a king by force: queen; rook, 2 bishops, bishop and knight, or pawn (can become queen). Two knights can legally mate but cannot force mate.
Mobility (Dan) The number of moves a piece has. The sub-types:
1) Potential mobility - the number of moves a piece would have from a given square if the board was empty. For example, a queen's potential mobility on e4 is 27.
2) Actual mobility - the number of moves a piece has in a any given position. e.g. In the initial setup, each knight's actual mobility is 2.
3) Global mobility - the number of future squares a piece can land upon in any given position. e.g. A bishop's global mobility is only 32
MCO Modern Chess Openings. A classic opening encyclopedia now in its 15th edition.
Monster (Dan) A piece which is worth considerably more than that piece's normal average value. e.g. "That knight is a monster!"
Motif A basic type of tactic, e.g. pin, skewer, double attack, discovered attack, removal-of-the-guard, etc.
NCO Nunn's Chess Openings. A competitor to MCO
Notation The recorded moves of a game. Note that you don't "notate" a game - you record it.
NTD National Tournament Director
Open File One with no pawns of either color
Open Game A game with lots of open files, especially the d and e-files. Alternately, a game that begins 1.e4 e5.
Outpost A piece guarded in a hole (a weak square on the opponent's side of the board).
Overpreparation (Dan) Taking (wasting) tempos to continue to prepare a move which, if played immediately, would be safe and reasonable anyway.
Patzer; fish A weak chess player
Pawn The weakest chess piece; can promote to another piece, other than a king.
Pawn Chain A series of pawns on contiguous files, usually where most of the pawns protecting at least one other (see "Pawn island")
Pawn Grabber A player who likes to take pawns even if the resulting gain may be marginal or even negative. If badly negative see "Poisoned Pawn"
Pawn Island A series of pawns on contiguous files; unlike pawn chain, there is no connotation that any pawns need protect each other.
Pawn structure How the pawns for one side are currently placed on the board.
Piece 3 Definitions, depending upon context:
1. All the chess men, as in “Get all the pieces out of the bag”
2.The non-pawns, as in “You have to develop all your pieces”
3. A Bishop or Knight, as in “I am up (ahead) a piece”
Pin An attack by a Rook, Bishop, or Queen, on a piece that cannot/should not move because a piece behind the attacked piece along the line of attack is worth even more (if the piece behind is a King, this is an “absolute” pin) and the piece is not allowed to move, or it would put the King into check, which is illegal.
Playing Strength The currently established ability of a player. If a rating were perfect, it would match the playing strength.
Ply A half-move, or the move of one player. When both players move, that is two ply, or one full move.
Poisoned Pawn A pawn that if taken will lead to detrimental play, such as loss of material.
Potential Mobility (Dan) See Mobility
Promote What a pawn does that reaches the other side of the board. The moving player replaces it with a Queen, Rook, Bishop, or Knight on the promoting square. So you can have nine Queens, maximum.
Pseudo-sacrifice A move which gives up material but involves no risk since the player making the move will get back or the material or more (or mate) by force in the next few moves. Many basic combinations start with pseudo-sacrifices, which is why a player cannot reject a candidate move just because it gives up material on the initial sequence.
PV Principal Variation – the predicted best moves for both sides (usually used in conjunction with computer analysis).
Quiescence Error The error of stopping analysis too quickly (thinking the resultant position is "quiet") when there are further forcing moves which strongly affect the evaluation of the sequence.
Quick Chess Chess played at a fast time control; for USCF this is usually 5-29 minutes for a game.
Race chess (Dan) Chess played without an increment or time delay (can deteriorate into a position where whoever moves faster wins)
Ram A pawn of each color against each other on the same file so that neither can move, e.g. White pawn e4, Black pawn e5 (Kmoch: Pawn Power in Chess)
Rank The rows of a chessboard going sideways, numbered 1st-8th starting from White’s side as 1st
Rating A quantitative measure of skill. USCF Ratings are based on a formula originally postulated by Dr. Arpad Elo, and range from roughly 100 for beginners to 3200 for the top computers.
Record To write down the moves of a game (verb). The noun is notation. Note that there is no chess verb "notate"
Real Chess (Dan) For every move you consider whether a possible opponent reply of a check, capture, or threat can be met.
Registration The time period before an event (but at the event) where players can sign up and play. To do so before that by phone, mail, etc. is "pre-registration".
Removal of the Guard - A tactical motif where the defender is captured or forced to move so that it is no longer defending. Usually seen in the form of Deflection or Overworked Piece.
Resigns When you purposely turn down your King or say “I resign” – the game is over and you lose. Note that shaking hands does not end a game.
Retained Image The analytical error that occurs deep in a line where a player visualizes a piece as still on a specific square, when in earlier moves of that visualized line it had moved off that square.
Round The game number in a tournament, e.g. I have two wins and one loss and now am going to play round four. A tournament usually has a fixed number of rounds.
Round Robin A system of pairing players where everyone in the same (small) section plays everyone else. Unlike a swiss system, this type of tournament calls for some level of commitment on the part of the players to attempt to complete all their games. The number of rounds in a single round robin is the number of players minus one.
Rut When a player is unable to improve or raise his rating despite consistent effort.
Sandbagger Someone who purposely keeps his rating low in order to qualify for easier sections and a better chance to win money.
Scholar’s Mate To mate on f7 (or, for Black, f2) with a Queen or a Bishop in 4 moves – usually a very bad thing to try. When teaching about this, Dan calls this “Dumb and Dumber”.
Section A part of a chess tournament where the players are paired together. Sections may be divided by rating class, scholastic vs. non-scholastic, rated vs. unrated, Scholastic Level, etc.
Seeds of Tactical Destruction (Dan) Aspects of a position that might allow the opponent to play a tactic, e.g. loose pieces, weak back rank, vulnerable king, pieces along a geometric line, overworked pieces, etc.
Semi-Open File A file with only pawns of the opponent. A semi-open game is one where both sides have semi-open (but not open) files.
Senior Master Someone with a US Chess Federation rating over 2399
Simultaneous Exhibition Also called "Simul" - One player plays multiple players at the same time. If the games are not played contiguously but instead a clock is used on each board, that is a "clock-simul"
Skewer/ X-ray Tactical Motif: An inside-out pin. A move that attacks a piece of value, and there is a piece behind it along the line of attack of equal or lesser value that will be attacked anyway if the attacked piece moves.
Skittles Chess for fun or chess without a clock; A skittles room is where you go and play for fun while waiting for your next formal pairing.
Slow chess Chess played at long enough time controls where good moves are generally more important than the time remaining. Usually at least 30 minutes per side.
Slump When a player consistently plays below his normal average playing strength
Sneaky Pin Taking advantage of the squares that a pinned piece is not guarding (Hertan)
Stalemate When the player to move isn’t in check, but none of his pieces can move. This is a type of draw (not all draws are stalemantes!)
STD Senior Tournament Director
Sudden Death A time control period where all the moves have to be played within a certain amount of time (on that player’s clock).
Swindle A successful risk taken when a player is losing and purposely does not play the best move in the hopes that the opponent will make a mistake, and then that happens. A swindle sets a "trap" by making a less-than-optimum move to complicate the position.
Swiss-Sys A software program to pair tournaments and provide tournament information
Swiss System A system of pairing tournaments whereby players are paired against other players who are doing about as well as they are. Wherever possible, players get about an equal number of games with Black and White, and will not play the same opponent twice.
Switcheroo A type of problem where you must switch ANY two pieces on the board and leave Black in a legal checkmate. Switching pawns to the 1st or 8th rank is not allowed. See Jeff Coakley's Winning Chess Puzzles for Kids books
TD Tournament Director (internationally this is an "arbiter")
t/d Time delay - the amount of time a digital clock waits before your official time begins decrementing. Usually this is 5 seconds for over-the-board US Chess Federation play. This differs from an increment, which adds time to your clock.
Tabiya Arabic word originally meaning the opening setup of pieces, but now more commonly used to mean the standard moves of any opening, i.e. the real game starts after the players play the tabiya.
Tactical Justification Any tactics necessary to make a move safe. Usually this means that, at first glance, the move may not look safe, but its safety is ensured by this tactic.
Tactical Vision The ability to spot basic safety issues (motifs like pins, double attacks, removal of the guard, and Counting) when first analyzing a position
Tactics A forcing set of moves that involves piece safety and checkmating. This includes:
1) En Prise (can take a piece for free)
2) Counting (is each piece safe from potential capturing sequences?)
3) Motifs (pins, double attacks, removal of the guard, etc.)
4) Non-sacrificial combinations of motifs
5 Sacrificial combinations
Team Tournament A tournament where the players play in rating order, first board against first, second against second, etc. The result is a team win, loss, or draw, depending on whether most of the players win or lose (or half of them do).
Tempo The “time” it takes for one of the players to make one move. A “turn”.
The Exchange See "Exchange, the"
Threat A move which can win material, checkmate, or make progress next move if the opponent does not stop it. Attacks on under-defended pieces are a examples of a threat.
Three-Fold Repetition of Position A type of draw where the same position is reached three times with the same player to move. Does not require the same moves and can occur at any point in the game.
Tie When two players have the same score in a tournament or match. Not when a game is drawn.
Tiebreak A method used for differentiating places between two players with the same score. It is usually based on how well the opponents did in an event.
Time Control How much time one has for a game. "G" means all the moves and "SD" is sudden death, meaning that time control requires all the remaining moves must be played in a specified period.
Time Delay The preferred way of using a clock at a USCF tournament; a digital clock is set to NOT run for the first N seconds on each move. Time is not added, as it is with a time increment.
Time Increment See "Increment"
Time Management The skill of taking care of your clock time during a chess game, at two levels:
1) To spend almost all your time for the game ("Macro time management") and
2) Where you spend more time on moves that require it (critical, complicated, etc.) "Micro time management" See The Two Move Triggers
Touch Move The rule that says:
1) If you purposely touch a piece you have to move it,
2) If you let go of a piece you have to leave it there
3) If you purposely displace an opponent’s piece, you have to take it.
Trade To exchange one piece for another of the same or similar value. NOT the same as "the Exchange"
Trap (Opening Trap) A known opening sequence where a player apparently follows good opening principles but the move is not tactically sound. Cambridge Springs trap: 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Nbd7 5.cxd5 exd5 6.Nxd5?? Superficially reasonable to grab the pawn when the f-knight is pinned, but... 6...Nxd5! 7.Bxd8 Bb4+ 8.Qd2 Kxd8 and Black will end up ahead a piece. (Compare: Blunder; Swindle)
Trigger One (Dan) Finding a move such that there can't be a better one (thus triggering a player to make that move)
Trigger Two (Dan) A reasonable amount of time to make a move, given the position, the time control, the times on the clock, and possibly the move number.
Two Bishops Short for "The advantage of the two bishops" - See "Bishop Pair"
Two-way bishop (Dan) - a bishop that is strong on both diagonals
Underpromotion When a pawn promotes, but the moving players chooses to get something other than a queen.
Unrated An unrated player who has never played a rated game, or one whose rating has not yet become official. An unrated game is one that will not be played for a rating.
USATE US Amateur Team East - one of the world's biggest team tournaments, held over President's Day weekend at the Hilton in Parsippany.
Visualization The ability to keep track of where the pieces have moved during lines of analysis
Wallchart A more complete crosstable posted at events showing the player's name, rating, ID, opponents, color each round, and results. Wallcharts show an individual's score cumulatively; crosstables show each game's result
Weak square A square which can no longer be guarded by a pawn.
Woodpusher A weak chess player
World Champion (WC) - the player who has won the official world championship event (tournament or match). Could be in a particular type, e.g. Junior or Women's World Champion.
Zugzwang When one side has to move, but any move is bad. Note: Some contend it is not true zugzwang unless the opponent could not win without this compulsion (in other words, if the player to move could pass but your opponent can still win then, although any move is bad, it is not a true zugzwang).
Zwischenzug An in-between move. For example, after a capture, instead of re-capturing, you give a check first. Sometimes called an "intermezzo".
960 Chess Also known as Fischer Random chess. A variant where the pieces are placed randomly on the back rank with certain rules such as bishops of opposite colors, king between rooks. There are 960 possible starting configurations.