Absolute pin
A pin where the piece behind is the king. The pinned piece cannot legally move if doing so would expose its king to check.
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Chess Glossary
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A
5 termsAdjusting a piece
Straightening a piece on its square without intending to move it. In tournament play, tell your opponent first, often by saying ‘I adjust’.
Algebraic notation
The standard way of recording chess moves using piece letters, square names and symbols.
Annotation
A note or symbol added to a game to explain an idea or comment on a move.
Arbiter
An official who oversees a chess event, applies its rules and handles disputes.
B
10 termsBack rank
The rank on which a player’s king and major pieces start: rank 1 for White and rank 8 for Black.
Back-rank mate
A checkmate delivered along the opponent’s back rank, often when their own pawns restrict the king’s escape.
Backward pawn
A pawn that falls behind nearby friendly pawns and cannot safely advance, often leaving a weak square in front of it.
Bishop
A piece that moves any number of unobstructed squares diagonally and stays on its starting square colour.
Bishop pair
Having both your light-squared and dark-squared bishops. Together they can control squares of both colours.
Blitz chess
Chess played at a fast time control, usually with only a few minutes per player.
Blunder
A serious mistake that significantly worsens a position, such as losing a queen or missing checkmate.
Board
The 8 × 8 grid of 64 alternating light and dark squares on which chess is played.
Bullet chess
Very fast chess, often with one minute or less per player. It is an informal time-control label rather than a standard FIDE category.
Bye
A round in which a player does not play a game. Depending on event rules, the bye may award points or no points.
C
14 termsCalculation
Thinking through possible moves and responses to see what positions might arise.
Candidate move
One of the moves you are considering seriously before choosing what to play.
Capture
To move your piece onto a square occupied by an opposing piece, removing that piece from the board.
Castling
A special move involving your king and one rook. The king moves two squares towards the rook, then the rook moves to the square beside the king on its other side.
Centre
The middle of the board, especially d4, e4, d5 and e5. Controlling central squares often gives pieces more freedom.
Check
A position where your king is attacked. You must respond with a legal move that gets your king out of check.
Check symbol (+)
A plus sign after a move in notation means the move gives check.
Checkmate
A position where the king is in check and the player has no legal way to escape. The game ends, and the player delivering checkmate wins.
Checkmate symbol (#)
A hash sign after a move in notation means the move delivers checkmate.
Chess clock
A pair of linked timers used so each player has a set amount of thinking time. Pressing your clock starts your opponent’s timer.
Chess rating
A number used by a rating system to estimate a player’s results-based playing strength. Different organisations and time controls may have different ratings.
Classical chess
A format with longer thinking time than rapid or blitz, commonly used in serious over-the-board events.
Combination
A planned sequence of moves, usually involving forcing ideas, that achieves a concrete result.
Connected passed pawns
Two or more passed pawns on neighbouring files that can often support each other as they advance.
D
9 termsDead position
A position where neither player can possibly checkmate the other by any sequence of legal moves. It is a draw.
Development
Bringing pieces from their starting squares to useful positions, particularly in the opening.
Diagonal
A line of squares that touch corner to corner. Bishops always travel along diagonals.
Discovered attack
An attack revealed when one of your pieces moves out of the way of another.
Discovered check
A check created when a piece moves and uncovers an attack on the opposing king from a piece behind it.
Double attack
One move that creates two threats at once. A fork is one type of double attack.
Double check
A move that gives check with two pieces at the same time. The defending king must move because neither capture nor block can stop both checks at once.
Doubled pawns
Two friendly pawns on the same file. They can be awkward to advance or defend, although they may also control useful squares.
Draw
A game result in which neither player wins. A draw can arise through stalemate, agreement and several other rules.
E
4 termsEn passant
A special pawn capture. If an opposing pawn moves two squares from its starting square and lands beside your pawn, your pawn may capture it as though it had moved only one square.
Endgame
The later stage of a chess game, usually with fewer pieces remaining. King activity and pawn promotion often become especially important.
Exchange
Trading one piece or pawn for another. The word ‘the exchange’ also refers specifically to the material difference between a rook and a bishop or knight.
Exchange sacrifice
Giving up a rook for a bishop or knight to obtain compensation elsewhere.
F
8 termsFianchetto
Developing a bishop on the long diagonal behind a pawn moved one square forwards, usually on b2, g2, b7 or g7.
Fifty-move rule
A player may claim a draw after 50 moves by each player without any pawn move or capture, provided the other requirements are met.
File
A vertical column of eight squares, labelled a to h from White’s left to right.
Fivefold repetition
When the same position occurs five times under the repetition rules, the game is automatically drawn.
Forcing move
A move that gives the opponent few sensible replies, such as a check, capture or direct threat.
Fork
A move that attacks two or more targets at once, using a single piece.
Forsyth–Edwards Notation (FEN)
A compact text description of a chess position, including which side moves next, castling rights and other game-state details.
Fortress
A defensive setup the stronger side cannot break through, even if it has more material.
G
2 termsGambit
An opening idea where a player deliberately offers material, usually a pawn, in return for time, activity or another advantage.
Game analysis
Looking back over a game to understand decisions, mistakes and missed opportunities. It can be done alone, with another player or with an engine.
H
2 termsHalf-open file
A file with none of your own pawns on it but at least one opposing pawn.
Hanging piece
A piece that can be captured and has no adequate defence, often simply because it has been left unprotected.
I
4 termsIllegal move
A move that breaks the rules, such as moving a bishop like a rook or leaving your king in check.
Increment
Extra seconds added to a player’s clock after each move, under a time control that uses increments.
Initiative
The ability to make threats that force your opponent to react to your ideas.
Isolated pawn
A pawn with no friendly pawns on either neighbouring file. It may be weak because other pawns cannot protect it.
K
4 termsKing
The piece you must protect from checkmate. A king normally moves one square in any direction, provided it does not move into check.
Kingside
The half of the board containing the e-, f-, g- and h-files, where the kings begin.
Kingside castling
Castling towards the h-file rook, written O-O in notation.
Knight
A piece that jumps in an L-shape: two squares in one direction and one at right angles. It is the only piece that can jump over other pieces.
L
2 termsLegal move
A move permitted by the rules of chess. A legal move must not leave your own king in check.
Light square
One of the 32 lighter squares. The h1 square, at White’s bottom-right corner, is light.
M
7 termsMain line
A commonly played or heavily studied sequence of moves in an opening.
Major piece
A rook or queen, also sometimes called a heavy piece.
Mate in one
A position in which a player can deliver checkmate with their very next move.
Material
The pieces and pawns each player has remaining. A material advantage means having more or stronger pieces overall.
Minor piece
A bishop or knight, usually contrasted with the more powerful queen and rook.
Mobility
The number and quality of squares a piece can legally reach. A blocked-in piece has limited mobility.
Move number
A number used when recording moves. In standard notation, each numbered turn usually contains one White move and one Black move.
O
7 termsOpen file
A file with no pawns from either player on it. Rooks often work well along open files.
Opening
The first stage of a chess game, when players usually develop pieces, fight for the centre and make their kings safer.
Opening principles
Helpful general ideas for the opening, such as controlling the centre, developing pieces and protecting the king. They are guides, not rules that always apply.
Opening repertoire
The openings and lines a player chooses to use regularly with White or Black.
Opposition
A situation where two kings face one another with a square between them. Whose turn it is can determine which king must give way.
Outpost
A useful square, often in the opponent’s half, where a piece can settle without being chased away by an opposing pawn.
Over-the-board chess (OTB)
Chess played face-to-face on a physical board, rather than online.
P
12 termsPassed pawn
A pawn with no opposing pawns ahead of it on its own file or either neighbouring file to stop it on the way to promotion.
Pawn
A piece that moves forwards but normally captures one square diagonally forwards. It can promote if it reaches the far end of the board.
Pawn chain
A group of friendly pawns protecting one another diagonally. The pawn nearest the back is the base of the chain.
Pawn structure
The arrangement of both players’ pawns, which helps shape plans, weak squares and open lines.
Piece
A general word for a chess unit. In everyday conversation it includes pawns, though players sometimes distinguish pawns from the other pieces.
Piece activity
How useful and influential a piece is in its current position, including the squares it can reach or control.
Piece value
An approximate guide to a piece’s usual strength, often using the pawn as one unit. Position and activity can matter more than the numbers.
Pin
A piece is pinned when moving it would expose a more valuable piece or important target behind it.
Plan
A connected idea for improving a position over several moves, which should be adjusted if the position changes.
Portable Game Notation (PGN)
A common text format for storing a full chess game, including moves and optional details such as player names and result.
Promotion
When a pawn reaches the farthest rank, it must become a queen, rook, bishop or knight of the same colour.
Promotion square
The square on the eighth rank for a White pawn, or first rank for a Black pawn, where it would promote.
Q
3 termsQueen
A powerful piece that can move any number of unobstructed squares along a rank, file or diagonal.
Queenside
The half of the board containing the a-, b-, c- and d-files, where the queens begin.
Queenside castling
Castling towards the a-file rook, written O-O-O in notation.
R
6 termsRank
A horizontal row of eight squares, numbered 1 to 8 from White’s side of the board.
Rapid chess
Chess played with a shorter time limit than classical but more time than most blitz games.
Resignation
When a player voluntarily ends the game and accepts defeat, usually because they believe their position cannot be saved.
Rook
A piece that moves any number of unobstructed squares horizontally or vertically.
Rook endgame
An endgame in which rooks are the main remaining pieces alongside kings and usually pawns.
Round
One scheduled set of games within a tournament. Players usually have one opponent in each round.
S
13 termsSacrifice
Deliberately offering material to gain another benefit, such as an attack, development or a winning position.
Scoresheet
A sheet used to record the moves of a game in notation, usually in longer over-the-board formats.
Seventy-five-move rule
A game is automatically drawn after 75 moves by each player without a pawn move or capture, unless the final move delivers checkmate.
Side to move
The player whose turn it is to make the next move.
Skewer
An attack on a valuable piece with another piece behind it. When the front piece moves, the one behind can be captured.
Space
Room for your pieces to operate, often created by controlling squares farther into the opponent’s half of the board.
Square
One of the 64 spaces on a chessboard. Each has a name, such as e4 or b7.
Square colour
Whether a square is light or dark. A bishop stays on the same square colour throughout a game.
Stalemate
A draw that occurs when a player is not in check but has no legal move available.
Standard Algebraic Notation (SAN)
The formal system used to write a single chess move, such as e4, Nf3, O-O or Qxd5+.
Starting position
The arrangement of all 32 pieces before the first move of a standard chess game.
Strategy
The longer-term choices and plans that help improve your position, such as where to place pieces or which pawn structure to aim for.
Swiss-system tournament
A tournament format where players have a fixed number of rounds and are generally paired with opponents on similar scores, without everyone playing everyone else.
T
8 termsTactic
A short, concrete sequence of moves that takes advantage of a position, often through threats or forcing moves.
Tempo
A unit of time measured in moves. Gaining a tempo means achieving something useful while making the opponent spend a move responding.
Threefold repetition
A player may claim a draw when the same position, with the same player to move and the same legal possibilities, has occurred at least three times.
Time control
The amount of time players receive for a game, sometimes with extra time added after each move.
Touch-move rule
In organised over-the-board play, deliberately touching one of your own pieces generally means you must move it if it has a legal move. Touching an opponent’s piece generally means you must capture it if legally possible.
Tournament
An organised event where players compete in a series of chess games according to its rules and format.
Transposition
Reaching the same position by playing moves in a different order.
Triangulation
A manoeuvre, often by a king, that returns to the same arrangement but changes whose turn it is.
U
2 termsUndefended piece
A piece not protected by another friendly piece. It may or may not currently be in danger.
Underpromotion
Promoting a pawn to a rook, bishop or knight instead of a queen.
V
1 termVariation
A particular sequence of moves within an opening or an analysed position.
W
1 termWeak square
A square that is difficult for a player to defend with pawns and may become a useful home for an opposing piece.
X
1 termX-ray
An attack or line of influence through another piece towards a target beyond it.
Z
2 termsZugzwang
A position in which having to move makes your situation worse, because every legal move gives something up.
Zwischenzug
A German word for an in-between move: playing an unexpected, often forcing move before making an otherwise obvious reply.