Chess glossary — terms of the course

An in-between move

A move played instead of the expected reply, for example instead of recapturing. Usually it is a check, a capture or a threat that the opponent must answer. After it the expected move is still possible, but the position is now more favourable. Chapter 17 · The in-between move and blunders

attacks

A piece attacks a square (keeps it under attack) if it could capture an enemy piece there on its next move. It also defends its own piece standing on that square. Chapter 2 · Rook, bishop, queen

backward pawn

A pawn whose neighbouring pawns have advanced, while the square in front of it is hit by an enemy pawn. It cannot safely move forward, and the square in front of it becomes weak. Chapter 28 · Pawn structure

bad bishop

A bishop whose own pawns stand on squares of its colour and block its diagonals. It defends pawns but hardly attacks anything itself. Chapter 23 · The French and the Caro-Kann

battery

Two line pieces of the same colour on one line, one behind the other: the front piece goes forward and the rear piece supports it. Chapter 2 · Rook, bishop, queen

blockade

A piece on the square directly in front of an enemy pawn. The pawn cannot advance, and it cannot drive the blockading piece away. Chapter 29 · The passed pawn

blunder

A gross mistake after which a player loses a piece, misses a mate or ruins the position at once. A blunder can usually be seen at a glance, if you look in time. Chapter 17 · The in-between move and blunders

breakthrough

A sacrifice of one or more pawns after which one of the remaining pawns becomes passed and promotes. Chapter 29 · The passed pawn

candidate moves

A move worth checking by calculation in a given position. The list of candidates is drawn up before calculating: forcing moves first, then moves with a strong threat. Chapter 38 · Calculation and judgement

candidate pawn

A pawn of a pawn majority with no enemy pawn in front of it on its own file. It is pushed first to create a passer. Chapter 29 · The passed pawn

capture

A move onto a square where an enemy piece stands: that piece is removed from the board and the capturing piece takes its place. Chapter 2 · Rook, bishop, queen

castling

A move of the king and a rook together: the king goes two squares along its rank towards the rook, and the rook jumps over it onto the next square. It is possible only if neither the king nor that rook has moved yet. Chapter 6 · Castling and draws

centre

The four squares in the middle of the board: d4, e4, d5 and e5. A wider centre is sometimes taken to be the sixteen squares from c3 to f6. Chapter 1 · The board and the pieces

check

An attack on the king: an enemy piece attacks the square the king stands on. You must answer check at once, on your very next move. Chapter 5 · Check, checkmate and stalemate

checkmate

A check that cannot be answered: the king has nowhere to go, nothing can capture the checking piece, and the check cannot be blocked. Checkmate ends the game at once and the side that gave it wins. Chapter 5 · Check, checkmate and stalemate

combination

A chain of forced moves, usually with a sacrifice, after which a player mates or wins material. The opponent's replies in a combination are forced, so it can be calculated to the end. Chapter 19 · Sacrifice and combination

connected rooks

Two rooks of one side with no pieces between them on their rank: they defend each other. In the opening the rooks connect when the minor pieces are developed, the king has castled and the queen has left the first rank. Chapter 10 · How to start a game

coordinates

The name of a square: the letter of its file (a to h) and the number of its rank (1 to 8), for example e4. The letter always comes first. Chapter 1 · The board and the pieces

dark-squared bishop

The bishop that moves on dark squares; in the starting position it stands on c1 for White and on f8 for Black. Chapter 2 · Rook, bishop, queen

dead position

A position in which neither side can give checkmate by any series of legal moves. The game ends in a draw at once, as soon as such a position appears. Chapter 6 · Castling and draws

Decoy

A technique in which an enemy piece, most often the king or queen, is lured onto a particular square by a sacrifice. A fork, a discovered check, mate or another blow awaits it there. Chapter 15 · Deflection and decoy

defend

A piece defends a friendly piece if it could recapture should the enemy take it. It is not the same as an attack: you attack enemy pieces and defend your own. Chapter 1 · The board and the pieces

Deflection

A technique in which an enemy piece is driven from its post by a sacrifice, a check or a threat. Once it leaves, it no longer defends the square, piece or line, and the blow it was holding back gets through. Chapter 15 · Deflection and decoy

development

Bringing pieces out from their starting squares to squares where they take part in the game. In the opening you develop the knights and bishops first. Chapter 10 · How to start a game

diagonal

A slanting line of squares of one colour that touch each other at the corners. The longest diagonals, a1–h8 and h1–a8, run from corner to corner and have eight squares. Chapter 1 · The board and the pieces

discovered attack

An attack that opens when a piece moves off the line of one of its own long-range pieces. The back piece strikes, while the piece that moved makes its own move at the same time: it checks, captures or attacks another target. Chapter 14 · Discovered attack and double check

discovered check

A check given by a piece that did not move: one of its own pieces opened the line to the king by moving off it. The piece that moved can meanwhile capture or attack anything it likes. Chapter 14 · Discovered attack and double check

double attack

A move after which two of the opponent's targets are under attack at once: two pieces, a piece and the king, or a piece and mate. The opponent can usually meet only one of the threats. Chapter 11 · Double attack and the fork

double check

A check from two pieces at once. It can be answered neither by capturing nor by blocking: the only defence is to move the king. Chapter 5 · Check, checkmate and stalemate

Doubled pawns

Two pawns of one colour on the same file. The rear one gets in the way of the front one, and they do not protect each other. Chapter 28 · Pawn structure

doubled rooks

Two rooks of the same colour on one file (less often one rank), one behind the other. Chapter 2 · Rook, bishop, queen

en passant

The capture of an enemy pawn that has just moved two squares past your pawn, made as if it had moved only one square: it can be played only at once, on the very next move. Chapter 4 · The pawn

endgame tablebases

The precomputed result of every position with a few pieces: for each one it records how the game ends with best play from both sides and in how many moves. Chapter 9 · First checkmates

evaluation of a position

The number an engine uses to describe a position: the advantage in pawns from White's point of view. Plus is better for White, minus for Black, around zero is equality. Chapter 27 · How an engine judges a position

fianchetto

Developing a bishop onto the long diagonal after moving the neighbouring pawn: the bishop goes to g2, b2, g7 or b7. Chapter 22 · The Sicilian Defence

file

A column of eight squares running from White's side to Black's. Files are named with the letters a to h. Chapter 1 · The board and the pieces

fool's mate

The fastest possible mate in chess: White opens the diagonal to their own king with two pawn moves, f and g, and Black's queen mates on h4 at once. Chapter 1 · The board and the pieces

fork

A double attack by one piece: it attacks two enemy pieces at once, or a piece and the king. Knights and pawns fork most often. Chapter 11 · Double attack and the fork

fortress

A position in which the defending side holds the draw despite a material deficit: the opponent can neither break through nor create threats that cannot be met. Chapter 37 · Bishop-and-knight mate, queen against pawn, fortresses

gambit

An opening in which one player gives up a pawn on purpose, sometimes more, for quick development, open lines or an attack. Chapter 21 · Open games

good bishop

A bishop whose central pawns stand on squares of the other colour. The pawns do not block its diagonals, and together they hold squares of both colours. Chapter 32 · Bishop against knight

Greek gift

A bishop sacrifice on h7 (or h2) with check: Bxh7+ Kxh7, then the knight checks from g5 and the queen comes to h5. It works when Black has no knight on f6 and cannot defend h7. Chapter 33 · Attacking the king

half-open

A file with none of your own pawns on it but with an enemy pawn. A rook on a half-open file presses on that pawn and the squares in front of it. Chapter 22 · The Sicilian Defence

Hanging pawns

Two connected pawns on neighbouring files (usually c and d) with no pawns of their own on the files next to them. They hold the centre, but only pieces can defend them. Chapter 28 · Pawn structure

hanging piece

A piece or pawn under attack that the opponent can capture at a profit: nobody defends it, or it is attacked by a cheaper piece. Chapter 8 · Piece values and trades

hypermodernism

A chess school of the 1920s. Its idea: the centre can be controlled by pieces from a distance, and the opponent's pawn centre can be attacked instead of occupying the centre with pawns at once. Chapter 25 · Indian defences and the English Opening

isolated pawn

A pawn with no pawns of its own colour on the neighbouring files. It cannot be defended by a pawn, and the square in front of it is a base for the opponent's pieces. Chapter 28 · Pawn structure

key squares

A square from which the king ensures its pawn promotes, however the opponent defends. For a pawn on its second to fourth rank these are the three squares two ranks in front of it. Chapter 35 · Pawn endings

kingside

The half of the board on the files from e to h, where the kings stand in the starting position. Chapter 1 · The board and the pieces

light-squared bishop

The bishop that moves on light squares; in the starting position it stands on f1 for White and on c8 for Black. Chapter 2 · Rook, bishop, queen

line pieces

A rook, bishop or queen (also called a sliding piece): a piece that goes along one straight line for any number of squares until it meets another piece. Chapter 2 · Rook, bishop, queen

Lucena position

A rook ending in which the pawn stands on the seventh rank, its king on the promotion square, and the enemy king is cut off. The stronger side wins by building a rook “bridge” against the checks. Chapter 36 · Rook endings

luft

A free square next to a castled king, made by moving one of the pawns in front of it, most often the h-pawn. It saves the king from a back-rank mate. The German word Luft means air. Chapter 18 · Mating patterns

material

All the pieces and pawns a side has, except the king. Material is counted in pawns: a pawn is 1, a knight and a bishop 3, a rook 5, a queen 9. Chapter 8 · Piece values and trades

minor pieces

A knight or a bishop, a piece worth about three pawns. The rook and the queen are called major pieces. Chapter 8 · Piece values and trades

minority attack

An advance of two pawns on the wing where the opponent has three. The aim is to trade and leave the opponent with a weak backward or isolated pawn. Chapter 24 · Closed games

mobility

The number of squares a piece can move to. The more it has, the more active the piece. Chapter 2 · Rook, bishop, queen

notation

A way of writing the moves of a game in letters and numbers. The notation used all over the world is algebraic: a letter for the piece, coordinates for the square, for example Nf3, exd5, O-O. Chapter 7 · Writing the game down

open file

A file with no pawns on it at all. A rook on an open file hits it from end to end and can go along it into the opponent's camp. Chapter 31 · Open files and the seventh rank

opening repertoire

The set of openings a player always plays: their own first move as White and their answers as Black to the opponent's main first moves. Chapter 26 · Building a repertoire

opening trap

A well-known opening position in which a natural-looking move loses material or leads to mate. Traps are set in the hope that the opponent will not check the reply. Chapter 20 · Opening principles and typical mistakes

opposite-coloured bishops

Bishops that move on squares of different colours: one side has a light-squared bishop, the other a dark-squared one. They never meet and can never be traded for each other. Chapter 32 · Bishop against knight

opposition

The position of the kings on one file or rank with one square between them: each takes away from the other the three squares in front of it. This is the close opposition; the distant and the diagonal opposition belong to pawn endings. Chapter 9 · First checkmates

outpost

A weak square in the opponent's camp that a pawn of your own protects. A piece on an outpost cannot be driven away by a pawn, and the opponent has to trade a piece of their own for it. Chapter 30 · Weak squares and outposts

outside passed pawn

A passed pawn far from the other pawns, usually on an edge file. It draws the opponent's king to the edge of the board, while your own king collects the pawns on the other wing. Chapter 29 · The passed pawn

Overloading

A situation in which one piece defends two squares or two pieces at once. Make it carry out one of its duties, and the other is left undefended. An overloaded defender is a target for an exchange or a sacrifice. Chapter 16 · Overloading and removing the defender

passed pawn

A pawn with no enemy pawns in front of it on its own file or the neighbouring files. Only pieces can stop it. Chapter 29 · The passed pawn

pawn break

A pawn move that attacks an enemy pawn and opens lines. A pawn break changes the pawn structure and often starts active play. Chapter 24 · Closed games

pawn chain

Pawns of one colour standing on a diagonal so that each defends the next. The bottom pawn of the chain is its base, and no pawn defends it. Chapter 23 · The French and the Caro-Kann

pawn island

A group of pawns of one colour on neighbouring files, separated from the other pawns of that colour by at least one file with none of them. Chapter 28 · Pawn structure

pawn storm

An advance of several pawns against the opponent's king. The pawns drive the defenders away, open lines and clear the road for the rooks and queen. Especially strong with castling on opposite sides. Chapter 33 · Attacking the king

Pawn structure

The placement of both sides' pawns. It changes slowly and decides which lines are open, which squares are weak and what plans the sides have. Chapter 28 · Pawn structure

perpetual check

A series of checks that the king cannot escape for good: one side gives check on every move, the positions start repeating, and the game ends in a draw. Chapter 6 · Castling and draws

PGN

Portable Game Notation, a text format for recording a chess game: first tags in square brackets (who, where, when, result), then the moves in standard English letters. Chapter 7 · Writing the game down

Philidor position

A rook ending in which the defending king stands in front of the pawn and the rook holds the third rank from its own side. When the pawn reaches that rank, the rook goes back and checks from behind. A draw. Chapter 36 · Rook endings

A position where a piece stands on the line of an enemy long-range piece and shields a more valuable piece behind it. If it shields the king, the rules forbid it to leave the line; if it shields the queen or a rook, it may leave, but what is behind it will be attacked. Chapter 12 · The pin

plan

A goal several moves ahead and the way to reach it: which weakness to attack, where to put the pieces, which pawn break to prepare. A plan follows from the evaluation of the position. Chapter 34 · Plans and prophylaxis

promotion

The replacement of a pawn that reaches the last rank by a queen, rook, bishop or knight of its own colour, on the same move and at the player's choice. Chapter 4 · The pawn

Prophylaxis

A move or manoeuvre that hinders the opponent's plan before they can carry it out. It starts with the question: what does the opponent want to do? Chapter 34 · Plans and prophylaxis

protected passed pawn

A passed pawn protected by a pawn of its own. The opponent's king cannot take it and has to guard it. Chapter 29 · The passed pawn

queenside

The half of the board on the files from a to d, where the queens stand in the starting position. Chapter 1 · The board and the pieces

quiet move

A move in a combination that is neither a check nor a capture. It usually sets up a threat the opponent cannot meet, or takes away the last squares from the opponent's pieces. Chapter 38 · Calculation and judgement

rank

A row of eight squares across the board, from left to right. Ranks are numbered 1 to 8. Chapter 1 · The board and the pieces

Removing the defender

A technique in which the defender of a piece or square is captured, traded off or removed with a sacrifice. After that, what it was defending is left undefended and is lost. Chapter 16 · Overloading and removing the defender

rule of the square

A way to tell without counting whether a king catches a passed pawn. The square runs from the pawn to its promotion square; if the king can enter the square on its move, it catches the pawn. Chapter 29 · The passed pawn

sacrifice

A move by which a player gives up material on purpose: a piece, a pawn or the exchange. In return they expect mate, more material or a strong attack. Chapter 19 · Sacrifice and combination

Scholar's Mate

Mate by the queen on f7 (or on f2, if Black delivers it) in the first moves of a game: the queen and a bishop together attack a pawn that only the king defends. Chapter 10 · How to start a game

seventh rank

The opponent's second rank, counting from their edge: the seventh for White, the second for Black. A rook there attacks the pawns that have not yet moved and shuts the king in on the edge rank. Chapter 31 · Open files and the seventh rank

skewer

An attack by a long-range piece on a valuable piece with another enemy piece behind it on the same line. The valuable piece steps out of the attack, and the attacker takes the piece that stood behind it. Chapter 13 · The skewer and the x-ray

smothered mate

Mate by a knight against a king whose neighbouring squares are all occupied by its own pieces. You cannot block a knight's check, and the king has nowhere to go. Chapter 18 · Mating patterns

square

One of the 64 squares of the chessboard. Every square has a colour and a name, for example e4. Chapter 1 · The board and the pieces

stalemate

A position in which the side to move has no legal move and its king is not in check. Stalemate ends the game at once as a draw. Chapter 5 · Check, checkmate and stalemate

starting position

The arrangement of the pieces before a game: pawns on the second and seventh ranks, rooks in the corners, then knights, then bishops, the queen on the square of her own colour, the king next to her. Chapter 1 · The board and the pieces

static evaluation

The evaluation of a position without calculating moves: a sum of terms such as material, piece mobility and pawn structure. The engine calls it at the end of every line it calculates. Chapter 27 · How an engine judges a position

tempo

One move as a measure of time. To lose a tempo is to make a move that adds nothing; to gain a tempo is to make the opponent spend a move for nothing. Chapter 10 · How to start a game

The back-rank mate

Mate by a rook or queen on the first rank (the eighth for Black) against a king shut in by its own pawns. One of the most common mates in games between beginners and club players. Chapter 18 · Mating patterns

the bishop pair

A light-squared and a dark-squared bishop on the same side. Together they attack squares of both colours, and in an open position the pair is valued a little above a bishop and a knight. Chapter 8 · Piece values and trades

the box

The part of the board in which the opponent's pieces have shut the king: it cannot leave it until the box opens. Chapter 9 · First checkmates

the endgame

The final stage of a game, when few pieces are left on the board. Chapter 9 · First checkmates

the exchange

The difference between a rook and a minor piece, a knight or a bishop. To win the exchange is to get a rook for a minor piece; to give up the exchange is the reverse. Chapter 8 · Piece values and trades

the fifty-move rule

A draw on the claim of the player on the move if each side has made 50 moves in a row without a single capture and without a single pawn move. Chapter 6 · Castling and draws

the opening

The start of a game, usually the first ten to fifteen moves, when both sides bring out their pieces, fight for the centre and tuck their kings away. Chapter 10 · How to start a game

threefold repetition

A draw on the claim of the player on the move if the same position has appeared in the game for the third time: the same pieces on the same squares, the same side to move and the same possibilities for both sides. Chapter 6 · Castling and draws

trade

A capture that the opponent answers with a capture: each side gives up a piece. An equal trade is a piece for a piece of the same value. Chapter 8 · Piece values and trades

transposition

Reaching a known position by a different move order. The position is the same as after the usual moves, although the moves were made in another order. Chapter 26 · Building a repertoire

waiting move

A move that changes nothing important in the position except whose turn it is: you make it so that your opponent has to move. Chapter 9 · First checkmates

weak square

A square that no pawn can defend any more: the pawns on the neighbouring files have advanced past it or disappeared. An enemy piece on such a square stands firm. Chapter 30 · Weak squares and outposts

x-ray

The action of a long-range piece through another piece, its own or the opponent's: it defends or attacks the square behind it. While the front piece stays put, the blow is hidden; when it moves or is taken, the line opens. Chapter 13 · The skewer and the x-ray

zugzwang

A position in which every move worsens the position of the side to move, and passing is not allowed. Most common in the endgame. Chapter 35 · Pawn endings