Chess Dictionary & Terms

A special pawn capture rule in chess that occurs immediately after a player moves a pawn two squares forward.

A tactical maneuver where a single piece attacks two or more of the opponent's pieces simultaneously.

A tactic where a defending piece is restricted from moving because doing so would expose a more valuable piece to capture.

A tactical attack on two pieces in a line, similar to a pin, but the more valuable piece is in front.

A situation where a player is forced to make a move that will significantly weaken their position.

A standard notation for describing a particular board position of a chess game.

A situation where the player to move is not in check but has no legal moves.

A special move involving the king and a rook, used to improve king safety and activate the rook.

A position where the king is in check and has no legal move to escape, ending the game as a win for the attacking side.

A tactic where moving one piece reveals an attack from another piece behind it along the same line.

An intermediate move inserted before an expected reply, often changing the evaluation of a sequence.

Developing a bishop to the long diagonal by moving a wing pawn one square and placing the bishop on g2/b2 or g7/b7.

A unit of time in chess: one move. Gaining a tempo means forcing the opponent to waste a move.

A king-and-pawn endgame concept where kings face each other with one square between them; the player not to move holds the opposition.

A very bad move that loses significant material or the game, usually marked as ?? in chess notation.

The standard system for recording chess moves using square coordinates (e.g. e4, Nf3, O-O).

A checkmate delivered by a rook or queen against a king trapped behind its own pawns.

A knight checkmate in which the enemy king is completely boxed in by its own pieces.

A check revealed when one piece moves away from the line of a bishop, rook, or queen.

One move that creates two threats at the same time, making both difficult to answer.

A tactic that forces a defending piece away from a square, line, or duty it must protect.

A tactic that lures an enemy piece onto a specific square where another combination works.

Eliminating a piece that protects a tactical target or prevents a decisive threat.

A piece required to defend two or more important targets and unable to maintain every duty.

Placing a piece between an enemy defender and the piece or square it protects.

A hidden line attack through an intervening piece, often by a bishop, rook, or queen.

A tactic that vacates a square, rank, file, or diagonal so another piece can use it.

A repeating series of discovered checks and captures that lets one piece collect material.

An unavoidable sequence of repeated checks that normally produces a draw by repetition.

Deliberately giving up material to gain time, activity, attack, structure, or another advantage.

Giving up a rook for a bishop or knight to gain non-material compensation.

Promoting a pawn to a rook, bishop, or knight instead of the usual queen.

Replacing a pawn that reaches the last rank with a queen, rook, bishop, or knight.

A pawn with no opposing pawn able to stop it on its file or either adjacent file.

A pawn with no friendly pawns on either neighboring file.

Two friendly pawns on the same file, usually created by a capture.

A pawn unable to advance safely and behind neighboring friendly pawns on adjacent files.

Connected pawns arranged diagonally so each pawn protects the one ahead.

A group of connected pawns separated from other friendly pawns by one or more files.

Advancing fewer pawns against a larger opposing pawn group to create a structural weakness.

A protected square in enemy territory that cannot be challenged by an opposing pawn.

A file containing no pawns of either color, providing an entry route for rooks and queens.

A file with no friendly pawn but at least one enemy pawn.

A square that cannot be defended effectively by a pawn and can be occupied by enemy pieces.

Control of more territory, giving pieces greater freedom and restricting the opponent.

The ability to make threats that force the opponent to respond.

Anticipating and preventing the opponent's plan before carrying out your own.

Play based on long-term features such as structure, space, squares, and piece quality.

Play dominated by forcing moves, concrete calculation, and short-term threats.

Analyzing concrete move sequences in the mind before choosing a move.

A short list of serious moves selected for calculation in a position.

An assessment of which side stands better and why in a given position.

An engine evaluation unit equal to one hundredth of a pawn.

An engine announcement that forced checkmate exists in a specific number of moves.

The engine's current best line for both sides from the analyzed position.

A measure of how many plies ahead a chess engine has searched in its main calculation.

An engine extension that continues forcing moves until a tactically unstable position becomes quiet.

Reaching the same chess position through a different order of moves.

A move known from established opening theory or an opening database.

A new move or important new idea introduced in a known opening position.

An opening in which material, usually a pawn, is offered for development or initiative.

A gambit offered in response to an opponent's gambit or aggressive opening move.

An opening beginning 1.e4 e5, often producing rapid development and open central lines.

An opening beginning 1.e4 followed by a Black reply other than 1...e5.

An opening beginning 1.d4 d5 or, more broadly, a position with locked central pawns.

A defensive setup that cannot be broken despite an apparent material disadvantage.

A maneuver that returns a piece to the same square after three moves while changing whose turn it is.

A fundamental winning rook endgame with a pawn on the seventh rank and its king in front.

A key drawing method in rook versus rook-and-pawn endings.

Moving a rook up a rank and across the board to join an attack or defense.

Two or more line pieces aligned to increase pressure along a file, rank, or diagonal.

Stopping an enemy pawn by placing a piece directly in front of it.

The material difference between a rook and a bishop or knight.

Having pieces or pawns of greater total value than the opponent.

A draw that may be claimed when the same position occurs three times with the same legal possibilities.

A draw claim available after fifty moves by each side without a pawn move or capture.

A draw because no legal sequence can produce checkmate with the remaining pieces.

A tournament rule requiring a deliberately touched piece to be moved or captured when legal.

The amount of clock time and any increment or delay assigned to each player.

Clock time added to a player's remaining time after every completed move.

Winning because the opponent's clock reaches zero before the game ends on the board.

A direct attack on the king that must be answered immediately by a legal move.

The degree to which a king is protected from checks, mating attacks, and forced exposure.

Moving pieces from their starting squares to active positions where they influence the game.

Influence over the central squares e4, d4, e5, and d5.