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.
