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Chess definitions of tems

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Accept To take an offered piece, as in the King's Gambit Accepted opening 1. e4 e5 2. f4 exf4. See also "Decline".
Active An aggressive move, line of play, or position. When mentioned in regards to a playing style, it indicates sharp or tactical tendencies.
Active defense The use of attack as a defense, rather than passively trying to cover weaknesses.
Active piece A developed piece that is actively participating in the conduct of the game. Active pieces form the basis of any attack.
Advantage Where the current position of the game favours one side over another. A material advantage refers to having a higher point count than the opponent. A permanent advantage is one with a lasting effect, such as an advantage in material or superior pawn structure. A positional advantage is an advantage in time, space, mobility, pawn structure, or control of critical squares. A temporary advantage is one that may eventually disappear, such as a lead in development.
Alertness The ability to take advantage of the opponent’s inaccuracies while playing accurately yourself.
Algebraic notation The modern and most popular way of recording chess moves, using single letter piece identifiers and unique alphabetic file and numeric rank identifiers.
Alpha-Beta pruning A technique used by computer programmers to cut down on the number of possible moves a computer has to evaluate before choosing the best move.
Analysis Calculation of possible moves and variations for a position.
Annotation Written comments about a game or position. May include variations from the main line of play.
Artificial castling To exchange the positions of the king and rook other than by castling. Also known as "Castling by hand".
Artificial manoeuvre Trying a bit too hard, or making an odd use of pieces.
Attack 1. An aggressive move or series of moves in a certain area of the board.
2. Threatening the capture of a piece or pawn or an empty square.
Back rank The first rank on the board for each player. It can become weak late in the game if the rooks don't cover it enough.
Backward pawn 1. A pawn at the base of a pawn chain that can't move forward due to one or more enemy pawns on the adjacent files.
2. A pawn which stands on an open file and cannot be protected by any other pawn.
Bad bishop A bishop whose movement is restricted by friendly pawns on its colour squares. These friendly pawns are in turn restricted by enemy pawns or pieces, thereby being unable to vacate squares for the bishop.
Base of pawn chain The very last pawn in a diagonal chain. It is the weakest point due to it not being supported by another pawn.
Battery A lineup of pieces that move similarly on a single file or diagonal, usually pointing toward a critical point in the enemy's camp. Batteries can be created by Queen and Rooks on a file or rank, and Queen and Bishops on a diagonal.
Berserker A rash playing style characterized by frenzied attacking with one or two pieces, perhaps with little regard for strategy or danger.
Bind Where a player is so tied up he has trouble finding useful moves. See "Squeeze".
Bishop pair Two bishops against a bishop and knight or two knights. Two bishops are effective together because they control diagonals of both colours, and work very well in open positions. See "Opposite colour bishops".
Blockade Immobilization of an enemy pawn by placing a piece (preferably a knight) on the square directly in front of it.
Blockading square The square directly in front of an isolated or backward pawn. This square can also serve as an outpost square, as an occupying piece cannot be chased away by pawns.
Blunder A horrible mistake where material is lost, serious tactical or positional concessions are made, or the game is lost.
Book 1. Published opening theory.
2. The library of opening moves maintained by a computer chess playing program.
Book Player A person who memorizes opening theory. Taking someone "out of book" refers to avoiding theory and playing a new or unorthodox move, which may confuse a book player.
Break A pawn move that proposes a pawn trade in order to increase space or relieve a cramped position.
Breakthrough Penetrating the enemy's position, whether by a pawn break or the sacrifice of pieces or pawns.
Brilliancy A game containing a very deep strategic idea, a beautiful combination, or an original idea or plan.
Broad pawn centre Three or four centre pawns abreast, which indicate very aggressive intentions. The opponent of such a "big centre" must look to restrain it and break it up.
Buried piece A piece hemmed in by friendly pieces and pawns. Such a piece will have a difficult time actively participating, and may also interfere with the development of other pieces.
Calculation The working out of variations mentally, without moving the pieces.
Candidate move A move considered as a starting point in the analysis of variations.
Capped pawn A marked pawn with which a player engages to deliver checkmate, in giving extreme odds to a weaker opponent.
Capture Moving a piece to a square occupied by an enemy piece, thereby removing the enemy piece from the board, out of play. Once a piece is captured, it may never return to the game.
Castle 1. The act of moving the king and rook simultaneously. This is the only time in the game where two pieces can be moved in the same turn. Castling consists of moving the king two squares either right or left, and placing the rook on the square beside the king closest to the centre. There must be no pieces between king and rook, neither piece may have already moved, and the King may not move out of Check, over it, or into it. Castling is usually worthwhile because it moves the King to a safer position in the wings behind pawns, and the rook to a more powerful position in the centre of the board at the same time.
2. Unsophisticated term for Rook.
Castle long Queenside castling.
Castle short Kingside castling.
Centralisation To move pieces towards the centre. This can be useful if there is no obvious alternative plan.
Centre The four centre squares e4, d4, e5 and d5. The area bounded by c3, c6, f3 and f6 is also considered central. The d and e files are the centre files. The centre of the board is of great strategic significance, as pieces placed there generally have the greatest scope.
Centre break The attack on two or more pawns abreast on the 4th rank by an opposing pawn in order to break up their formation.
Centre fork trick A series of moves where a knight is sacrificed for a centre pawn, knowing that it can be recovered by a pawn fork and the enemy's central pawn structure will be destroyed by doing so.
Centre pawns The king’s and queen’s pawns.
Centralize Placing of pieces and pawns so they both control the centre, and influence other areas of the board. Pieces usually have maximum mobility (and therefore power) when centrally placed.
Check The act of attacking the opponent's king. When check takes place, a player usually calls out "check" so the opponent is aware of the threat. The opponent must get out of check on the next move, either by moving the King, capturing the attacking piece, or moving another piece between the King and the attacking piece.
Checkmate Threatening the capture of the enemy king such that it cannot escape. This wins the game for the attacking side.
Chessmen Pieces.
Classical 1. A playing style based on the formation of a full pawn centre. The strategic concepts involved are seen as ultimate laws, and therefore rather dogmatic.
2. An era where all players used this style and those that did not were considered irregular.
Clearance A move that clears a square for use by a different piece. The new piece can use the square to better advantage. A "clearance sacrifice" is where the vacating piece is sacrificed to make room.
Closed game A position where the pawn structure is fixed, the centre cluttered with interlocked pawns. Knights thrive in such positions, and play is generally focussed on the flanks.
Combination A sacrifice and forced sequence of moves to gain a certain advantage.
Compensation An equivalent advantage that offsets an advantage of the enemy's, for example material vs. development, space vs. superior minor piece, or three pawns vs. knight.
Connected passed pawns Two or more same-colour passed pawns on adjacent files. See "Passed pawn".
Connected rooks When the two rooks are on the same rank or file, with no pieces or pawns between them. Rooks are very strong when they are connected, as they support each other.
Consolidate Taking care of your position before continuing active operations. This could mean adding protection to critical pawns or squares, improving the placement of pieces, or making the king safer.
Control The domination or sole use of a square, group of squares, file ordiagonal. One is also "in control" when one has the initiative.
Coordinates Unique square identifiers, made up of a number indicating rank and a letter indicating file.
Counterplay Aggressive actions by the defender. Counterplay may equalize the chances, may be not quite enough to equalize, or may seize the initiative and gain an advantage.
Counter attack The launch of an attack by the defender, rather than making more defensive moves. Designed to place the opponent on the defensive.
Counter threat See "Counter attack".
Cramped Disadvantaged in space, leading to a reduction in mobility of one’s pieces.
Cross-check A check in reply to a check. Typical of queen endings.
Critical position A point where the evaluation of the position will obviously favour one side, or where it will equalize. The position is delicately balanced and the slightest mistake could be disastrous.
Decisive A move which alters or makes certain the result of a game. A decisive move may make an advantageous position a winning one. A decisive error may lose the advantage or the game.
Decline To not take an offered piece, as in the King's Gambit Declined opening 1. e4 e5 2. f4 followed by any move except exf4. See also "Accept".
Decoy 1. The offering of material in order to get an enemy piece to move.
2. The lure of an opponent’s piece to a square that is particularly vulnerable.
Defense 1. Any move or plan that is intended to meet or stop an enemy's threats or attack.
2. Name used for openings initiated by black, such as Petroff Defense, French Defense. etc. These systems are called defenses due to black having the second move, and being forced to respond to white's first move.
Deflection A tactic which forces an opponent piece from a square where it had to be, either because it was defending a piece or square or because it was blocking a threat.
Destructive sacrifice Sacrificing material to destroy the pawn cover or other protection around the enemy king. Usually a point of no return.
Development The moving of pieces from their starting positions to new positions where their mobility and activity are increased. To bring pieces into play.
Diagonal A diagonal row of squares. Diagonals are named by the coordinates of their starting and ending squares.
Discovered attack The creation of an attack from one piece caused by the moving away of another piece that was masking it. These are potent moves, as they may enable a piece to move away from a threat in safety, or enables two attacks to be launched simultaneously.
Discovered check Check given by one piece as the result of the moving away of another piece that was masking it.
Dislodging manoeuvre A move to upset a defensive formation.
Distance The number of squares between two pieces. This is a crucial calculation in endgames to determine whether a king can stop a hostile passed pawn.
Double attack The launch of two threats simultaneously. It is different from a fork in that either or both threats need not be a capture.
Double check A simultaneous check given by moving one piece to give check, thereby also unmasking another piece which also gives check.
Doubled pawns Two pawns of the same colour on the same file, put there by a capture. These pawns are generally considered to be weak, but they can control valuable squares and create open or half-open files.
Draw A game that ends in a tie, where each player is awarded half a point. A draw occurs when 1) there's not enough material to force mate; 2) there is a stalemate; 3) a 3-time repetition of position has been reached, or 4) there is mutual agreement (see "Draw offer").
Draw offer The suggestion by one player to the other that they agree to call the game a draw. When playing manually, the correct way to make a draw offer is to make your move, say clearly "Draw?", and then start your opponent's clock. Never make a draw offer when it's your opponent's turn to move.
Dynamic Dynamics are represented by the aggressive potential in a move or position.
Dynamic play Dynamic play occurs as a result of frequent structural changes that demand constant reevaluation of one's strategy. These changes are usually as a result of tactical threats or significant changes in the pawn structure.
Echos Two functionally identical positions on the same board, one the mirror image of the other, due to the arrangement of the defender’s pieces being effectively symmetrical. This allows the same attack to be made down either side of the board.
Elo rating An internationally accepted mathematical system for ranking chess players, created by Arpad Elo. International Grandmasters are typically in the range 2500 to 2700, world champions often over 2700. The standard deviation is 200 points. The scale is such that a player at 1800 would be expected to beat one at 1600 by the same margin as a player at 2600 against one at 2400. Many games must be played before an Elo rating can be estimated with confidence. The Elo rating is the foundation for the award of FIDE titles.
Endgame The final phase of the game when there are few pieces left on the board. The endgame generally starts after queens have been exchanged or when the immediate goal is to promote a pawn.
En passant French "in passing." It occurs when a pawn moves two squares from its starting position, and passes an enemy pawn that has advanced to its fifth rank. The advanced pawn on the fifth rank may choose to capture the pawn as if the pawn had only moved forward one square. This capture must be made immediately after the two square advance, or else the right to capture "en passant" is lost. In some chess notations an en passant capture is labelled "e.p."
En prise French "in take" A piece or pawn that is unprotected and exposed to capture.
Equality Where neither player has a discernible advantage over the opponent.
Exchange A trade of pieces. Trading a minor piece for the opponent’s rook is called "winning the exchange". Trading a rook for the opponent’s minor piece is called "losing the exchange". See "Point count".
Exchange sacrifice Where a player willfully trades a rook for a minor piece in return for compensation of some kind. See "Compensation".
Expansion Increasing the amount of space directly under your control. To expand, push pawns forward in an attempt to increase the boundaries of your territory.
Fianchetto Italian "on the flank". The development of a bishop to b2 or g2 (b7 or g7 for Black).
FIDE Federation Internationale des Echecs, the world governing body for chess. Founded in 1924, it organizes world championship competitions, draws up rules of the game, and awards the international titles to top players.
Fifty move rule A game can be drawn when fifty moves have been made by each player without a capture or pawn advancement.
File A row of eight squares from one end of the chessboard to the other. In Algebraic Notation these are labelled a to h, starting from the queenside of the board.
Fixed centre Where the centre of the board is occupied by multiple pawns and some of them are fixed in place by opposing pawns. In some cases, pawn movement is possible but the advancing pawns will be subject to capture.
Fixed pawn structure Pawn set-ups where there is little or no possible mobility. Since there will be little pawn play, strategies are easier to determine.
Flank The files that do not belong to the centre, that is the a, b and c files on the queenside, and the f, g and h files on the kingside. Certain openings that focus on flank development are called "flank openings." Typical first moves for these openings are 1.c4; 1.b3; 1.Nf3; etc.
Flank attack Attacking on either the kingside or queenside. Such attacks are much more successful when the centre is closed.
Fluid pawn structure Structures where future pawn movement is likely. Strategy may be difficult to determine, as a change in the pawn structure necessitates a change in strategy.
Focal point A weak square near the enemy king. This is targeted by the attacker, and the defender may find it difficult to protect. More than one focal point makes an attack stronger.
Fool’s mate Checkmate in the manner of 1. f3 e3 2. g4 Qh4*
Force Your army. All pawns and pieces are units of force.
Forced A move or series of moves that must be played to avoid loss of the game or catastrophic loss of material.
Forcing move A move which leads the opponent into a forced move or moves.
Forepost An advanced square which cannot be attacked by a hostile piece of inferior rank. Foreposts are ideal squares for attacking knights as they have a short range. An absolute forepost is where the position is unassailable. A contingent forepost can only be attacked at the cost of creating a weakness elsewhere.
Fork A form of double attack where one piece threatens two enemy pieces at the same time. In a triple fork, three enemy pieces are threatened.
Fortress A defensive blockade to keep out the enemy forces, especially the king.
Forward Pawn A pawn that is at the very front of a pawn chain. It is the only pawn contained in the chain that does not protect another pawn.
Frontal assault A direct attack on an enemy pawn that is located on the same half-open file as your heavy pieces.
Gambit Italian "a trip up". Where the first player voluntarily sacrifices a pawn or piece in the opening for positional or developmental advantage. A counter-gambit is where the second player makes a similar sacrifice for similar aims.
General principles Basic rules that serve as guidelines for less advanced players. Basic rules don't apply to all situations, and more experienced players learn when to apply them in each specific position.
Ghosts Threats created in the mind of inexperienced players due to lack of confidence or fear of their opponent.
Good bishop 1. A bishop not hindered by friendly pawns on the same colour squares.
2. A bishop with adequate scope.
Grab Capture a piece, perhaps making a positional concession in the process.
Grandmaster The highest title (apart from World Champion) that a chess player can achieve. It is bestowed by FIDE upon players who have achieved certain performance norms. Abbreviation GM. Other titles (in order of importance) are International Master and FIDE Master.
Grandmaster draw A quick, uninteresting draw.
Half-open file A file with pawns of only one colour on it. This file is closed to the pawn owner, and open to the other player.
Hanging A pawn or piece subject to immediate capture. Also "En prise".
Heavy pieces Rooks and queens, also known as "major pieces" or "heavy artillery."
Hold To hang on, to allow a successful defense.
Hole A square that is undefendable by pawns. Such a square serves as an excellent home for enemy pieces, especially the knight.
Illegal move A move made contrary to the rules of chess.
Imbalance A noticeable difference between the white and black armies. This may include material advantage, superior pawn structure, space, development, the initiative, or a superior minor piece.
Impossible move A move which has obvious unfavourable results, and so is to be avoided.
Inactive piece A piece not directly involved in the flow of the game.
Initiative The player that is on the attack, or otherwise applying pressure to the opponent on the defensive, is said to "have the initiative."
Innovation A novel move or idea in an established line of play.
Insufficient material When neither player has enough pieces to mate their opponent. A draw is declared.
Interference move A move which obstructs the line of attack of an enemy piece.
International master The next highest title below Grandmaster. Abbreviation IM.
Interpose Placement of a piece between an attacking enemy queen, rook or bishop, and the piece being attacked.
Intuition A ability of an experienced player to decide on a move or plan by feel, rather than by extensive analysis.
Isolated pawn A pawn with no friendly pawns on the adjacent files. It cannot be protected by pawns, and the square directly in front of it can be a safe haven for enemy pieces as they cannot be threatened by pawns.
J’Adoube French "I adjust". Expression used prior to a piece being adjusted on its square.
Kingside The half of the board from which the king starts. The e, f, g and h files.
Knight on the rim A knight on the edge of the board. Unless it is performing a specific duty, its future is said to be "dim," as it attacks very few squares, none in the centre. It may even become trapped on the edge.
Liquidation 1. A series of exchanges that are done to slow or halt the enemy's attack.
2. To trade off in order to enter a drawn or won endgame.
Locked centre Similar to a fixed centre except that no pawn movement is possible.
Luft German "air." Moving a pawn so the king has an escape square to prevent back-rank mates.
Main line The principal variation used or analysed.
Major piece A rook or queen.
Manoeuvre A series of quiet moves designed to redeploy your pieces more favourably.
Master A player whose Elo rating is 2200 or higher. If the player's rating drops below 2200 the title is revoked.
Mate See "Checkmate".
Material Your pieces and pawns (excluding the king). See "Force".
Mating attack An attack against the enemy king that leads to possible checkmate, or where mate can be averted by the enemy sacrificing material. Either way, a winning advantage is obtained by the attacker.
Mating net A mating attack that leads to mate with correct play, no matter what the enemy does. A forced mating attack.
Middlegame The phase of the game between the opening and endgame. The middlegame generally commences after development has been completed by both sides.
Minor piece A bishop or knight.
Minority attack An attack on a pawn majority by a pawn minority. This usually occurs on the queenside. The idea is to force a pawn trade that creates a pawn weakness in the enemy pawn structure.
Mobility How much freedom of movement the pieces have. A piece's value is increased when it has more mobility, as it has more attacking power. See "Scope".
Notation A system of symbols and coordinates for recording the moves of a game. See "Algebraic notation".
Occupation 1. Placement of a rook or queen on a rank or file, or a bishop or queen on a diagonal, to exert control over it.
2. Placement of a piece safely on a square to exert pressure from it.
Open 1. A type of position (see "Open Game") or file (see "Open File").
2. A type of tournament in which any class of player can participate.
Open file A file where no pawns are present. Rooks are at their strongest when placed on open files.
Open game A position where there are few centre pawns, and many open attacking lines. A lead in development is crucial to exploiting an open position.
Opening The beginning phase of a game, usually the first 10-15 moves. It is characterized by rapid development of forces, control and/or occupation of the centre, and getting the king to safety. The real purpose of the opening is to create an imbalance in the enemy's camp, and development of pieces to exploit this imbalance.
Openings A specific sequence of moves which have been catalogued over time. Specific openings are often played because players have analysed them thoroughly and believe they are the best way to achieve the initiative. There are over 1000 openings and many, many more variations. Most are named after the player, region or type of moves that are played, such as the Alekhine Defense, King's Gambit and Sicilian Defense.
Opening book See "Book".
Opening library See "Book".
Opening repertoire A set of openings that a player prepares in advance to get to a preferred middlegame position.
Opposite colour bishops Where each side has only one bishop that travels on squares of a different colour from that of the enemy. This can be effective during an attacking middlegame, as the defending bishop cannot control the squares the attacking bishop travels on. In an endgame, opposite colour bishops generally signal a draw, as the defender can put his king and pawns on the opposite colour of the attacker's bishop.
Opposition An endgame term meaning the king not forced to move. Where the two kings stand on the same file or diagonal with an odd number of squares between them, the player that doesn't have to move is said to "have the opposition." This is important in king and pawn endings as the player who can secure the opposition can effectively guard certain spaces or drive the opposing king back.
Orientation The way the board is positioned. The correct way has each player with a white square in their right hand corner.
Outflanking A manoeuvre in the endgame with kings where one makes forward progress up the board while: 1) not allowing the opponent to gain the opposition, or 2) temporarily giving up the opposition in order to achieve a certain goal.
Outpost A safe square near or in enemy territory that is protected by friendly pawns or pieces, and subject to effective occupation by one of your pieces.
Outside passed pawn A passed pawn on the flank which is far from all the other pawns on the board.
Overextended The position after a failed offensive or advance, in which a player's position is left with various weaknesses and no compensation for them.
Overprotection Defending a strong point more times than appears necessary. The idea is that the overprotected pawn or square may be causing considerable problems for the opponent, who would be unwise to try to break the strong point, because he would release the latent power of the protecting pieces. See also "Prophylaxis".