Chess glossary
Chess Terms: The A–Z Glossary
Published Updated
103 chess terms used in games, books, videos and commentary, defined in plain English on one page. Jump by letter, and use the available links for full lessons and worked boards.
A
Algebraic notation
The standard way chess moves are written. Every square has a name built from its file letter and rank number (e4, f7), pieces are abbreviated K, Q, R, B and N, and pawns get no letter at all — so Nf3 is “knight to f3” and e4 is a pawn move. Full walkthrough: chess notation.
Attraction (decoy)
A forcing move, often a sacrifice, that draws an enemy piece onto a square where a follow-up tactic works: a fork, skewer, deflection, or mate. Tactical names overlap, so the same sequence may reasonably be described as attraction and deflection. Worked examples: attraction tactics.
B
Back rank
The rank where a player’s pieces begin — the first rank for White, the eighth for Black. A “weak back rank” usually means the king lacks a safe flight square and is vulnerable to a rook or queen entering with check.
Back-rank mate
Checkmate delivered by a rook or queen on the back rank against a king trapped there by its own pawns. See the back-rank tactics pillar for rated puzzles, and how to prevent it with luft.
Backward pawn
A pawn that cannot be supported by a neighbouring pawn as it advances, while the square in front of it is controlled by the opponent. It can become a target on a half-open file, although a pawn break or piece activity may make the apparent weakness temporary.
Battery
Two or more long-range pieces aligned on the same rank, file or diagonal — for example, queen and rook doubled on a file, or queen and bishop sharing a diagonal. The rear piece can support a capture by the front piece or add pressure to the same target.
Bishop
The minor piece that moves any number of squares diagonally and therefore spends the whole game on one colour. Worth about three points. Details and a board to try: how the bishop moves.
Bishop pair
Retaining both bishops, especially when the opponent does not. The pair can cover both colour complexes and work on two wings, so it is often valuable in open positions; closed structure, king safety and concrete tempi can outweigh that general preference.
Blitz
Fast chess. Under current FIDE rules, a game is blitz when each player’s allotted time is ten minutes or less, counting sixty times any increment. “Bullet” is an online convention within that range, and site labels differ. In 3+2, each player starts with three minutes and receives two seconds after every move. See time controls.
Blockade
Placing a piece directly in front of an enemy pawn — especially a passed pawn — to stop its advance. A knight is often a useful blockader because it can remain active from that square and the blocked pawn cannot attack it directly; other enemy pieces or pawns may still drive it away.
Blunder
A serious error such as hanging a piece, missing a mate or allowing a decisive tactic. Annotators often mark one with “??”, but the label is contextual rather than an official numerical threshold. A final scan of the opponent’s checks, captures and threats catches many one-move blunders.
Bullet
An online label for extremely fast chess, commonly below three minutes per player after allowing for increment. It is not a separate FIDE over-the-board category; such games fall within FIDE’s blitz range. See time controls.
C
Capture
Ordinarily, moving a piece onto a square occupied by an enemy piece, which is removed. Pieces capture according to their movement rules; pawns move straight but capture diagonally. En passant is the special exception in which the capturing pawn lands on the square the enemy pawn passed over.
Castling
The only move where two pieces move at once: the king steps two squares toward a rook and that rook hops to the king’s other side. Kingside castling is written O-O, queenside O-O-O. Five conditions must hold — see the castling rules.
Centre
The four central squares — d4, d5, e4 and e5 — and, in a broader sense, their immediate surroundings. Central control can increase piece mobility and influence play on both wings, but occupying a central square is useful only when the piece or pawn is secure.
Check
A direct attack on the king. The defender must answer immediately by moving the king, capturing the attacker, or — against a non-adjacent line check — interposing a piece. No move that leaves the king in check is legal. See check and checkmate.
Checkmate
Check with no legal answer: the king cannot move to safety, and no legal capture or interposition removes the attack. The game ends immediately — the king is never actually taken. Named patterns and mating methods are collected at the checkmates hub.
Combination
A calculated sequence that coordinates two or more tactical ideas to achieve a concrete result, often with forcing moves or a sacrifice. The defender may have branches; the combination is sound only if the intended result survives the relevant replies.
Connected rooks
Rooks standing on the same rank or file with nothing between them, so each can defend the other unless it is pinned or otherwise constrained. Connecting the rooks often follows development and king safety, but it does not by itself mark a fixed end to the opening.
D
Deflection
Forcing an enemy piece away from an essential duty — guarding a mating square, a back rank, or another piece — so that what it protected falls. The close cousin of overloading. Worked examples: deflection tactics.
Development
Bringing pieces into useful play in the opening, especially the knights and bishops that begin behind the pawns. Rooks may become connected or gain useful files without leaving their starting squares. A lead in development matters most when it can be converted into activity or forcing play. See opening principles.
Diagonal
A slanted line of same-coloured squares, such as a1–h8. Bishops and queens travel along diagonals; the longest two run corner to corner. See the board and its squares.
Discovered attack
Moving one piece out of the way to uncover an attack by a bishop, rook or queen behind it. The moving piece may create a second threat; when the uncovered attack is check, the defender must answer that check, but the moving piece is not automatically safe. See discovered attacks.
Double attack
A move that creates two threats at once. The fork is the one-piece version; a discovered attack may create threats with two pieces. A double attack wins something only when the defender lacks a move that answers both threats or creates a stronger counter-threat.
Double check
Check from two pieces at once, created when a moving piece gives check while uncovering another check. Blocking or capturing with a different piece cannot answer both attacks, so a legal king move is required; that move may capture one checker if the destination is safe. See double check.
Doubled pawns
Two pawns of the same colour on one file, normally created by a capture. They cannot defend one another directly and may be hard to advance, but the capture that created them can open a file, add central control or give one pawn useful mobility.
Draw
A tied game, normally worth half a point to each player. Draws may result from agreement, stalemate, a dead position, a valid threefold- or fifty-move claim, or automatic fivefold repetition or seventy-five moves. See draws in chess.
E
ECO code
A classification code from the Encyclopaedia of Chess Openings: a letter A–E plus two digits (B90 includes the Najdorf Sicilian). ECO groups opening positions and families rather than assigning a unique code to every named variation. Browse the openings library.
Elo rating
A rating approach named after Arpad Elo in which actual results are compared with expected scores derived from rating differences. FIDE uses a published Elo implementation; online platforms may use Elo, Glicko or proprietary variants. See Elo vs Glicko.
En passant
French for “in passing”: when an enemy pawn advances two squares and lands directly beside your pawn, you may capture it as if it had moved only one square — but only on your very next move. The full three conditions, with a board to try: en passant.
En prise
French for “in take”: a piece exposed to capture without adequate compensation. Before taking it, check recaptures, pins and counter-threats; see hanging pieces.
Endgame
The phase in which reduced material makes king activity, passed pawns and promotion especially important. Its boundary is positional rather than a fixed move number. Reference positions such as opposition, Lucena and Philidor provide tools, not answers to every ending. Start at the endgame hub.
Exchange, the
The specific trade of a rook (5 points) for a minor piece (3 points). The side gaining the rook has “won the exchange”; giving up a rook for a minor piece on purpose is an “exchange sacrifice.” See piece values.
Exposed king
A king with open lines leading towards it, inadequate pawn cover, or too few nearby defenders. Checks become candidate moves, but an attack needs enough pieces and may be met by exchanges, flight squares or a counterattack. See exposed-king tactics.
F
FEN
Forsyth–Edwards Notation: six fields describing a board snapshot — piece placement, side to move, castling availability, en passant target, halfmove clock and fullmove number. It does not contain the repetition history or earlier moves. Learn to read one at how to read PGN and FEN, or build one in the board editor.
Fianchetto
Developing a bishop to b2 or g2 (b7 or g7 for Black), normally after advancing the adjacent knight pawn — Italian for “little flank.” The bishop works on a long diagonal; if its king castles behind that structure, exchanging the bishop or moving the shelter pawns can change the king’s safety.
FIDE
The Fédération Internationale des Échecs, chess’s world governing body: it maintains the official Laws of Chess, the international rating list, and titles like Grandmaster. See FIDE titles.
Fifty-move rule
A player may claim a draw when the last fifty moves by each player contained no pawn move and no capture, subject to the prescribed claim procedure. At seventy-five moves the draw is automatic unless the final move checkmates. Details: the fifty-move rule.
File
A vertical column of eight squares, lettered a through h from White’s left. Rooks and queens move along files and can use an open or half-open one as an entry route. See the board and its squares.
Flag (flagging)
Running out of time — from the small flag on an analogue clock. Under the FIDE Laws, a player whose flag falls normally loses unless the opponent could not possibly checkmate by any legal sequence from the final position; in that case the game is drawn.
Fool’s mate
The fastest possible checkmate from the starting position: 1.f3 e5 2.g4 Qh4#. It requires White to make two weakening pawn moves and ignore the threat; the example shows how opening the diagonal to an uncastled king can permit an immediate mate. Step through it at fool’s mate.
Fork
One piece attacking two or more targets at once. The tactic wins material only if the defender cannot save both, capture the forking piece, or create a stronger threat. A “royal fork” attacks king and queen. See fork tactics.
Fortress
A defensive construction that cannot be breached without allowing a drawing mechanism, despite a material deficit. A fortress claim must survive concrete attempts such as pawn breaks, zugzwang, exchanges and king entry; material count alone does not prove it.
G
Gambit
An opening that offers material — usually a pawn — in exchange for faster development, open lines, or attacking chances. The Queen’s Gambit and King’s Gambit are well-known examples, although not every move called a gambit concedes material by force. Browse them in the openings library.
Glicko
A rating system that tracks a rating and a “rating deviation”, which represents uncertainty in the estimate. Glicko-2 also models volatility. New or returning players can move faster than established active players; implementations differ by platform. See Elo vs Glicko.
Grandmaster (GM)
FIDE’s highest open playing title. The usual route requires a 2500 rating threshold and GM norms covering at least 27 games; specified championship results can award direct titles. See the sourced FIDE titles guide.
H
Half-open file
A file containing pawns of only one colour. The side without a pawn there may use the file for rook pressure or an entry square. The file is an opportunity, not an automatic attack: pieces, pawn breaks and the squares beyond the pawn decide whether it is useful.
Hanging piece
A piece that can be taken without adequate tactical or material compensation. It is often undefended, but counting attackers and defenders is only the first check: piece values, recaptures, pins and in-between moves determine whether the capture is genuinely free. Train the pattern at hanging-piece tactics.
I
Initiative
The ability to pose threats that force useful replies, leaving the opponent little time for an independent plan. An initiative is temporary and may justify material investment only when the resulting activity and threats are concrete.
Insufficient material
Common shorthand for a dead position caused by the remaining material: no legal sequence can lead to checkmate. Bare kings, or king and one bishop or knight against a bare king, are standard examples. Two knights versus a bare king is different because mate is possible but not forcible. See dead positions and material.
Isolated pawn
A pawn with no friendly pawn on either adjacent file. It cannot currently be supported by another pawn and the square in front can become an outpost, but open files and active pieces may compensate for that structural weakness.
J
J’adoube
French for “I adjust”. Under the FIDE Laws, only the player whose turn it is may adjust pieces, and must first express that intention — commonly by saying “j’adoube”. Saying it after deliberately touching a piece does not cancel touch-move.
K
King
The piece the game is about. It moves one square in any direction, can never move into check, and can never be captured — the game ends at checkmate, one move before. Details and a board: how the king moves.
Kingside
The half of the board from the e-file to the h-file, where the kings start. “Castling kingside” (O-O) is the short, quick version; a “kingside attack” targets the king castled there.
Knight
The minor piece that moves in an L-shape — two squares then one at a right angle — and is the only piece that jumps over others. Worth about three points; it often benefits from secure central squares and closed structures. Details: how the knight moves.
L
Ladder mate
A mating method in which two major pieces — usually two rooks, or a rook and queen — take away neighbouring ranks or files in turn, driving a bare king to the edge. Each checking piece must remain safe from capture. See the ladder mate.
Luft
German for “air”: usually a pawn move in front of the castled king that vacates a possible flight square, such as h3 leaving h2 available. Luft can prevent a specific back-rank mate, but only if the flight square is safe; the pawn move may also weaken the king shelter.
Lucena position
A central theoretical winning position in rook endgames: the stronger side’s advanced pawn and king are sheltered from checks by a rook manoeuvre known as “building a bridge”. The exact conditions matter; learn them at the Lucena position.
M
Major piece
A queen or rook — the pieces strong enough to deliver mate with only their own king’s help. Also called “heavy pieces.” Compare minor piece.
Material
The total value of pieces on the board, counted with the standard points (pawn 1, knight and bishop 3, rook 5, queen 9). “Winning material” means coming out ahead in that count. The values, and their limits: chess piece values.
Middlegame
The phase between opening and endgame, usually after the initial development has established a pawn structure and competing plans. It has no fixed starting move: an opening can lead quickly to an ending or to a sharp middlegame while pieces remain undeveloped.
Minor piece
A bishop or knight, each conventionally worth about three pawns. Neither can force checkmate against a bare king with only its own king’s help. Their relative value depends on pawn structure, square access, open lines and play on one or both wings.
O
Open file
A file with no pawns of either colour. Rooks and queens can use it to contest entry squares, but ownership of the file matters only if a piece can penetrate or attack a useful target.
Opening
The first phase of the game, in which the sides develop, shape the centre and arrange king safety. Its length varies by position. Principles help in unfamiliar positions; concrete move-order knowledge matters when a line is forcing. Explore the opening guides.
Opposition
A relationship between kings used to control entry squares in pawn endings. In direct opposition the kings face each other with one square between them, and the side not to move can often force the other king to yield. Whether that wins or draws still depends on the pawn, key squares and board edge. Study opposition in king and pawn endings.
Outpost
A useful square, usually in enemy territory, where a piece is secure from an opposing pawn challenge. Pawn support makes an outpost more stable but is not part of every definition. Its value comes from the targets and restrictions the occupying piece creates, not from the label alone.
Overloaded piece
A defender assigned two or more duties that cannot all survive a forcing sequence. The tactic works only when the defender must answer one threat and no replacement can assume the abandoned duty. It is closely related to deflection.
P
Passed pawn
A pawn with no enemy pawn ahead of it on the same file or either adjacent file. That removes one class of blocker, but kings and pieces may still stop it, and an immediate push may be mistimed. See promotion.
Pawn
A piece that moves one square forward, may move two from its starting square when both squares are clear, captures one square diagonally forward, and never retreats. On reaching the last rank it must promote. Details and a board: how pawns move and capture.
Pawn structure
The arrangement of pawns: chains, islands, doubled or isolated pawns, passed pawns and open files. Because pawns cannot retreat, structural changes are lasting and often suggest plans, but piece activity, king safety and tactics remain part of the evaluation.
Perpetual check
A sequence of checks that the defending side cannot escape without unacceptable loss. It commonly leads to a draw by a correct threefold-repetition claim, or automatically after five occurrences of the same position.
PGN
Portable Game Notation: a widely supported plain-text format for game metadata and movetext, with optional comments and variations. Learn to read it at how to read PGN and FEN, or paste one into the PGN viewer.
Philidor position
A reference drawing setup in rook and pawn versus rook. With the required king and pawn geometry, the defending rook holds its third rank to keep the attacking king out, then switches to checks from behind after the pawn advances. Learn the conditions at the Philidor position.
Pin
An attack along a line against a piece that cannot (or dare not) move because a more valuable piece stands behind it. Absolute pins involve the king and make moving illegal. Worked examples: pin tactics.
Promotion
A pawn that reaches the last rank immediately becomes a queen, rook, bishop or knight of its own colour. A queen is the usual choice, while underpromotion may supply a unique check, avoid stalemate, or meet another concrete need. There is no limit based on the pieces already present. Rules and examples: pawn promotion.
Q
Queen
The strongest piece: rook and bishop combined, moving any distance along ranks, files and diagonals, worth about nine points. Details and a board: how the queen moves.
Queenside
The half of the board from the a-file to the d-file, where the queens start. “Castling queenside” (O-O-O) is the long form. A queenside majority or pawn advance may suggest play on that wing, but the centre, king positions and available breaks determine the plan.
Quiet move
A non-checking, non-capturing move. In a combination it may prepare a threat, remove a defence or leave the opponent in zugzwang; the threat need not be unstoppable. See quiet-move tactics.
R
Rank
A horizontal row of eight squares, numbered 1 (nearest White) to 8 (nearest Black). “The seventh rank” — the opponent’s second — is prized rook territory. See the board and its squares.
Rapid
A time-control category between blitz and standard chess. Under current FIDE rules, a game is rapid when the allotted time per player is more than ten minutes but less than sixty, counting a sixty-move increment allowance. Online labels can differ. See time controls.
Rating
A number estimating playing strength from results — FIDE Elo over the board, with Glicko-family systems used by major online platforms. Interpretation depends on the pool, time control and reliability of the estimate: see what is a good chess rating?.
Repertoire
The set of opening positions, move orders and plans a player has prepared for both colours. Its breadth and depth depend on the player’s competition and study time. Build and rehearse lines in the repertoire trainer.
Resignation
Conceding the game before checkmate. In over-the-board play, clearly state the resignation and stop the clocks; tipping the king alone can be ambiguous. Continuing a difficult position can be useful practice, while resigning a position you fully understand can save time.
Rook
The major piece that moves any unobstructed distance along ranks and files, conventionally worth about five pawns. Rooks take part in castling and often become active on open files or the seventh rank. Details: how the rook moves.
S
Sacrifice
Deliberately giving material for another form of compensation: mate, recovered material, promotion, development, structure or a sustained initiative. A tactical sacrifice has a calculable return; a positional or speculative one requires an honest evaluation of longer-term compensation. See sacrifice tactics.
Scholar’s mate
A four-move checkmate pattern in which queen and bishop attack f7: 1.e4 e5 2.Bc4 Nc6 3.Qh5 Nf6?? 4.Qxf7#. Black has several sound ways to meet the threat; see Scholar’s Mate.
Skewer
A line attack on a front target, often the king or queen, intended to expose a second target behind it after the front one moves. Captures, blocks and counter-threats can defeat the idea, so calculate the final exchange. See skewer tactics.
Smothered mate
Checkmate delivered by a knight when the opposing king is hemmed in by its own pieces and has no flight square. A familiar combination uses a queen sacrifice to force a rook beside its king before the knight mates, but not every smothered mate has that sequence. See smothered mate.
Stalemate
The player to move has no legal move and is not in check: an immediate draw, regardless of material. It can be an accidental error by the stronger side or a deliberate defensive resource. Examples and how to avoid it: stalemate.
Swindle
A practical escape from a losing position, obtained by setting a difficult problem such as a stalemate trick, perpetual check or tactical trap. The defensive try may also be objectively best; “swindle” describes the practical reversal, not the engine ranking of the move.
T
Tactic
A concrete move or sequence that uses threats, checks, captures or move-order details to achieve a result such as mate, material gain, promotion, perpetual check or a necessary defence. Pattern recognition supplies candidates; calculation tests them. Start at the tactics hub.
Tempo
One move treated as a unit of time. A move gains a tempo when it improves the position while forcing a useful response; a move loses time when its purpose could have been achieved more efficiently. Whether a repeated piece move is wasteful depends on what it accomplishes.
Threefold repetition
A draw may be claimed when the same position — same pieces, same player to move, same rights — occurs three times, not necessarily in a row. Details: threefold repetition.
Time control
The clock rules for a game: starting time, any increment or delay, and any staged additions after a specified move number. Labels such as bullet, blitz, rapid and classical vary between governing bodies and platforms. Guide: time controls.
Touch-move rule
Under the FIDE Laws, a player whose turn it is and who deliberately touches a piece on the board must move or capture the first touched piece when a legal move or capture exists, subject to the rule’s detailed order and exceptions. See touch-move.
Transposition
Reaching the same position through a different order of moves. One opening can transpose into another when piece placement, side to move and relevant rights match; the moves omitted along the way can also prevent a transposition.
Trapped piece
A piece that cannot find a satisfactory retreat after it is attacked or enclosed. Before calling it lost, check captures, counter-threats, exchanges and tactical escape squares. See trapped-piece tactics.
Triangulation
A manoeuvre, often by a king, that returns to the important arrangement while changing whose turn it is. It works only when the opponent has fewer useful waiting moves and cannot change the position meanwhile. Study triangulation and reserve tempi.
U
Underpromotion
Promoting a pawn to a rook, bishop or knight instead of a queen. A knight may supply a unique check or fork; a rook or bishop may avoid stalemate by controlling fewer squares. Compare all four legal promotions. See pawn promotion.
V
Variation
A specific sequence of moves — a branch of an opening (“the main line of the Najdorf Variation”) or a line of analysis (“in this variation Black holds”). Annotated games show variations alongside the moves actually played.
W
Waiting move
A move whose main purpose is to preserve the important features of a position while passing the obligation to act back to the opponent. It still changes the position and must not surrender a useful square or tempo.
Z
Zugzwang
German for “compulsion to move”: a position in which every legal move worsens the mover’s result or evaluation compared with being allowed to pass. It appears often in pawn endings and some blocked middlegames; opposition can be one route to it.
Zwischenzug
German for “in-between move” (also “intermezzo”): before the expected reply, often a recapture, a player inserts a more urgent check, capture or threat. The original continuation may follow later or be replaced altogether.
Missing a term?
This glossary covers a broad set of vocabulary used in games, books and commentary. Many entries link to a full lesson or worked example; for a structured route, start from the rules hub or the learning path.