Definitions

There is no "official dictionary of chess". Although chess writers usually mean the exact same thing when using a word (e.g. "winning the exchange"), sometimes they mean slightly different things such as "analysis" or "the opposition" or a "backward pawn" (see my video "What is a Backward Pawn?"). For more "textual" chess information, check out my Principles pages.

"(Dan)" preceding a definition means that the term is one I have created and use in my writings; all other terms are fairly standard around the chess world.

Term Definition

ABC Error (Dan) A thought process error of the following type: a player calculates a three-ply sequence ABC where: 1) move A is their intended move,
2) move B (likely opponent reply), 3) move C (their next move replying to B). They make move A, the opponent does reply B, and then   they make move C immediately without recalculating C or looking for a better move. If move A is OK but move C is a big mistake, then this is an "ABC error". It's a very common error made by low rated players.

Accidental Error      (Dan) - an error made with the best intentions but made due to human calculation error; not a purposeful error

Acquiesce                  (Dan) - To quickly make a losing move capitulating when there is adequate time on the clock and it was possible that more thought could/would produce a move that could save the game.

Action Chess            A game where each player has 30 minutes (or often 25 5) to make all his moves. Also known as "Rapid Chess"

Activity                      The positive actions a piece (or pieces) can do in a given position. In the opening, developing a piece correctly should give it more activity. e.g. in the endgame one should "activate" the king, often by centralizing it.

Actual Mobility (Dan) See Mobility

Advance Entries      The players who pre-registered (See "registration") for an event. Usually posted before an event.

Advantage of the two bishops - See "Bishop Pair"

Alekhine's Gun Putting both rooks and a queen on a file (usually an open file) with the queen behind the two rooks.

Algebraic Notation A method for writing moves down by using the names of the pieces and the ranks and files. FIDE officially replaced older Descriptive Notation (“P-K4" is now "e4") circa 1970.

Alpha Zero The Google neural network program that taught itself chess and beat the strongest digital program, Stockfish.

Amateur                      In chess, a non-master. At the US Amateur, masters cannot play. At the US Amateur Team tournaments, the team has to average below master rating. Note: in chess, amateurs can win money, sometimes quite a bit at tournaments like the World Open. In the United States, players with ratings below 2200 are considered amateurs

Analysis The part of the thought process where you generate candidates for both sides (the move tree), e.g. "If I go there, what would he do?"

Annotation                To write the story of a game, providing additional text and analysis showing what happened - or could have happened.

Arbiter A high-level tournament director, usually one who is in charge of an international tournament or FIDE match.

Artificially Castling See "Castling by hand"

Artificially Isolated A pawn that has at least one pawn on a neighboring file, but neighboring pawns are unable to guard or be guarded easily (usually one is stuck on a rank where it cannot move to support the neighboring pawn)

Assymetric pawn structure a pawn structure where the pawns are not exactly on the same files as all opponent's pawns.

Attack 1) When you move a piece to a square where you could capture an opponent’s piece NEXT move, e.g. 2.Nf3 attacks the e5 pawn 2) When you have either a) the initiative and can put pressure on specific squares or the opponent's king, or b) can make a series of forcing moves (checks, captures, and threats) that either threaten to mate or win material or can do so, e.g. I am attacking the kingside.

Attacker 1) a piece that is doing an attack on an opposing piece or 2) a piece taking part in an overall attack, such as participating in a mating attack.

Attraction Forcing a defensive piece to go to a square where it can be a target (somewhat the opposite of deflection).

AWL   (Dan) "Attack it with something Worth Less" - AWL is a strong type of threat, because it usually requires the defending piece to move. One cannot usually defend a piece attacked AWL because it will simply be captured, winning material. Most trapped pieces are done via AWL, and AWL moves are usually good candidates. 1.e4 d5 2.exd5 Qxd5 3.Nc3 is an example of AWL (knight attacks the queen).

Back Rank The rank where a player sets up his major pieces (1st for White; 8th for Black)

Back-Rank Mate     A checkmate on the 1st or 8th rank with a Rook or Queen where that piece also covers all the escape squares on that rank. Can also be made on the a or h-files

Backward Pawn    An unguarded pawn which, if you removed all the non-pawns on the board, can move, but eventually pushing it would lose material to opposing pawn captures (even if an adjacent pawn, currently on a lower rank, was able to advance and recapture).
Notes: 1) A pawn that is fixed (cannot move because another pawn is directly in front, i.e. a "ram") is, by definition not backward,
2) The rearmost pawn in a pawn chain is usually a NOT a backward pawn, but it is possible.
3) See the video (https://www.youtube.com/watch?v=vkGBr6TUMoY) for much more information.

Bad Bishop A bad piece is one with much less activity than normal, with not great prospects of getting more activity. So a bad bishop is usually one that is trapped in by its own pawns, and those pawns are relatively immobile, so moving them to activate the bishop is difficult.

Bailout move (Dan) A move in a complicated position where a player is unsure they can find the best, or even a safe move. It's a move that may clearly not be best, but at least it's fairly safe. A second definition is: a move that avoids complications, e.g. "He could have sacrificed his bishop but he bailed out with another move." In faster time controls or if winning easily playing a bailout move is not always a big error.

Barely adequately protected (or defended) - a piece that is attacked and defended just enough that it's capture would not lose material but not overprotected. Barely adequately protected pieces can be subject to tactics like double attack.

Battery Lining up two pieces that move similarly, like a Queen and Rook or Queen and Bishop.

Big Pawn A bishop that is being used as if it were a pawn, usually a bishop guarded by a pawn that is also guarding a pawn immediately diagonal above it. For example, if White has a pawn on f2 and d4, then playing Be3 creates a "big pawn".

Bind A situation, usually in the endgame, where one side has tied up the other side's forces, so that they have little or no scope & no constructive plan. The inferior side usually has safe moves, so they are not in zugzwang, but can't break out without the superior force letting them out.

Bishop The pieces that start the game on c1/f1/c8/f8 and move only diagonally as far as they can until they hit the end of the board, a piece of the same color, or up until a capture of an opposing piece.

Bishop Pair             (="The advantage of the bishop pair") When one player has two bishops and the other does not. On average, this is worth about half a pawn.

Black The player who moves second in a game, usually with the darker colored pieces.

Blindfold chess      A game played where one or both parties are not permitted to look at the board and pieces, but must visualize the entire game as they are dictated the opponent's moves.

Blitz                          Fast chess. Many blitz games are 5 minutes per player for the entire game. Chess played at a fast enough time control where good moves are generally less important than the time remaining.

Blockade A defensive pattern, usually against a passed pawn, where one places pieces on squares that make progress difficult for the other side.
  For example, if White has a passed pawn on d5, Black can blockade that pawn by placing a knight on d6.

Blocked Position A position with fixed pawns across most of the board, making it difficult for the two sides to conflict. (As opposed to just a "closed" position")

Blunder                    A bad move; primarily a move that turns a win into a loss or draw, or a draw into a loss. ANY bad mistake is a blunder - not just a Counting mistake, or allowing any simple tactic.

Board Vision          (Dan) - The ability to look at a chess board and (quickly) see what all the pieces are doing (statically). For example, seeing that a bishop on a1 is attacking h8. In Rapid Chess Improvement Michael de la Maza calls this "Chess Vision"

Book                         Besides the kind with a spine, a “book” move is one that a player has learned to play in a particular position in the opening (from a “book” or other media) without the need to “calculate”. The main book moves in a certain opening before a major deviation is a tabiya.

Bookup                    A chess program that enables one to store moves in a tree from the opening position, train, etc. Now "Chess Openings Wizard"

Botvinnik's Rule    A time management principle that states in "normal" openings you want to use roughly 20% of your time for your first 15 moves

Break move            Short for "pawn break".  A pawn move attacking an opponent's fixed pawn (thus forcing the possible "break up" of his pawn structure).

Brittle Describes a position with very low flexibility; i.e., the pieces are "tied up" and can't easily move without allowing tactics to the opposing player.

Bughouse               A variant of chess with two players on each side – a player gets the pieces his partner captures and may place one on an empty square in lieu of a "regular" move.

Bullet chess Chess played with an extremely short time limit, usually 1 0, 2 0, or 2 1 (The first number is the number of minutes each player has for the game; the second number is the increment: the number of seconds added to the clock after each move).

Bye                           What you get as a score when you can’t play a round, but still continue to play in the tournament. Byes don’t count for ratings, and can be either 0 points, ½ point, or 1 point (the latter in case you want to play, but are the odd person available). See also "forfeit". Guide to Byes

Calculation              The part of analysis involving forced sequences (more broadly, the part of analysis involving various move sequences and/or possible tactics)

Candidate (move)   A move under consideration (during the thought process). Some specific types of candidate types:
1) King of the Hill - the best candidate found so far.
2) Initial Candidate (Dan) - any move which does something positive (or any move under initial consideration)
3) Final Candidate (Dan) - a candidate which is safe (can't easily be defeated by a forcing move) & under final consideration

Candidate Master   (CM) - Someone with the International Chess Title for players rated 2200-2299 FIDE (also for a short time the USCF title now "expert")

Capture (or Take)   To remove a piece from the board via a legal move - not kill or eat (although other languages use these terms)

Castle Move an unmoved King 2 squares toward an unmoved rook and place the rook on the other side of the king; not a name for a rook.

Castling by hand To eventually put the king and a rook where they would normally castle, but to do so by moving each piece individually (requiring at least 2 king moves)

Castle long   "O-O-O" - To castle queenside by moving the king two squares toward the queen's rook and the queen's rook three squares past the king.

Castle short   "O-O" - To castle kingside by moving the king two squares toward the king's rook and the king's rook two squares past the king.

Center The middle of the board. Sometimes designated as just the d4/e4/d5/e5 squares.

Centralize To move a piece toward (into) the center of the board.

Cheating Most chess cheating involves surreptiously using an engine to tell you what moves to make. But cheating could involve many other issues, such as not following rules, getting help from other humans, consulting illegal material during a game, purposely distracting an opponent, etc.

Check                       An attack on the King. You do not have to announce “check”. By rule, the player in check must get out of check on his move by moving the king to a safe square, blocking the check, or capturing the checking piece.

Checks, Captures, and Threats - (Dan ) The three types of forcing moves. Note that threats to checkmate are more forcing than captures and sometimes even more than checks.

Checkmate ("mate") An attack on the king (see "check") where there is no way for the king to get out of check. It is essentially a proof that the king could be captured on the next move, if one more move was allowed.

Chessable Online site with many courses, server to play, etc.

ChessBase               An advanced chess database program that enables one to store and search games, etc.

Chess.com               The largest online chess website with ~93,000,000 "users" (2022). I had a show "Q&A with Coach Heisman" on Chess.com TV and we have a "Dan Heisman Learning Center" as a group there.

Chess Club An organized group that meets periodically (usually daily or weekly) where players can join, meet other players, & play chess games and/or organized events.

Chess.FM                 An online chess radio station open to Internet Chess Club members - Dan had a radio show, "Ask the Renaissance Man", now does Instructional Videos

Chess Match See "match"

Chess Maze             A type of board vision problem where you move one White piece multiple times in a row to capture the Black king. There are restrictions where it can move, e.g. can't move to squares guarded by Black pieces

Chess Tip of the Day A Twitter tip provided daily by Dan H, starting ~2010.

Chess Tournament   An organized chess competition, usually featuring multiple chess rounds), often played for prizes. Tournaments can be "open" to any participant, or restricted in some way like "scholastic" (for school children) or invitational (open to only those meeting certain criteria).

Chess24 Magnus Carlsen's comprehensive web site, host for many online GM events and place where you can follow OTB GM events, etc. Purchased by Chess.com in 2022 as part of the Magnus Group.

Clearance Opening up a square or line, usually with a sacrifice that gets a piece out of the way, for positive purpose. If the item being opened is a line (diagonal, rank, file), then this is known as "Line Clearance".

Closed File                A file containing pawns of both colors

Closed Position      A position without any open or semi-open files. If some pawns are immobile due to opponent pawns, see "Fixed Pawn Structure". The initial position of a game is a closed position (compare to a "blocked position" or one with many fixed pawns).

Club See "Chess Club"

CM                             Candidate Master - A FIDE title for those with FIDE ratings 2200-2299 (Dan is a CM).

Complex                 1) Complicated (not necessarily chess), also in chess: "Sharp"
2) A set of squares of the same color in one part of the board. e.g. "White has a weak dark square complex on the queenside."

Composition A challenging (usually endgame) problem, the type typically submitted to competitions. World Federation for Chess Composition

Consolidation         The period after winning material where the side behind in material has the initiative but the side ahead can eventually stabilize and take the initiative with his extra power.

Control   Usually referring to a situation where one side (or piece) attacks squares in a way that is currently unopposed, e.g. 1.e4 attempts to control d5 (and f5), or a rook on an open file that has no opposing rook on the file "controls" that file.

Coordination           The ability for various pieces to work together harmoniously to achieve a goal.

Counting                   (Dan) Seeing if pieces are safe from capturing sequences; the tactic that determines if any forced sequence of captures on any square or squares will gain or lose material.

Critical move            A move in a position where the best move(s) are enough better than the second best to make a difference in the expected outcome (win to draw or loss; draw to loss; easy win to difficult win). Critical moves often include complicated decisions, trading pieces, or inflexible plans which cannot be changed. One which should be played carefully and slowly.

Criticality Assessment - The ability to assess how crucial it is to determine the best move(s), i.e., their effect on the possible outcome. (The ability to differentiate the criticality of a move.)

Cross Pin To meet a pin by pinning the piece making the original pin. Example: FEN r1k1/p5pp/1p6/3q1p2/1PQ1R3/P1P3P1/5PKP/8 b - - 0 4

Crosstable               A chart showing how each player did in each round.

CTD                          Club Tournament Director

Dance Around A defensive idea in an endgame when a king needs to be on a certain square at a certain time, so it "dances around" on squares that touch that square waiting to go to it at the appropriate time. For example B:Ke4,pd5 W:Ke1,pd4 White to play 1.Kd2 loses to 1...Kxd4 & Black wins with the opposition, so White's king should "dance around" the d2 square and only go there after Black captures on d4: 1.Kd1 Kxd4 2.Kd2 =

DanHeismanChes s The name of my instructional video channel on Youtube. Over 320 videos as of earl;y 2023 and counting...

Dan's Metric             (Dan) The move number in a game where you first can state that all your non-pawns (except the King) are developed (active). Counting the number of pieces you have out would result in "Pariseau's metric", a useful guide for helping develop pieces efficiently.

Dead Draw An evaluation of a position, almost always in the deep endgame, that the game should end in a draw almost no matter how poorly either side could play (within reason).

Deep Blue The IBM chess playing program, hardware based, which played Garry Kasparov in two world-famous matches in 1996 & 1997, winning in '97.

Defense 1) When one player is attacking the other player is said to be playing defense. This also often applies to defending against someone with the initiative. 2) An opening for Black, e.g. The French Defense or The King's Indian Defense.

Deflection A tactical maneuver where a defensive piece is forced to move, thus "deflecting" it off of its defensive duties on its original square. This can be used as part of a removal-of-the-guard tactic or for other offensive purposes.

Delay See "time delay", as opposed to "increment"

Demonstration Board A large board set up so that a large audience can follow the moves of games or an instructor. In modern times many demonstration boards are electronic instead of physical.

Descriptive Notation  An old chess notation used primarily in English texts including moves such as "P-K4" or "NxB"

Desperado                  A "hanging" piece that is going to be captured anyway, so it may be possible to "sacrifice" itself to get the maximum return.

Develop To activate your pieces in the opening, e.g. 1.Nf3 develops the knight since it does more on f3 than it did on g1.

Development The status of your activation of your pieces in the opening, e.g. After 1.e4 d5 2.exd5 Qxd5 3.Nc3 Qd8 Black is somwhat behind in development since he moved his queen twice and is now back on his original square, undeveloped.

DGT Board An electronic chess board that can output the moves to a digital device like a computer so the user can play on a "real" board and send the moves over the internet to an opponent.

Discovered Attack    An attack by a piece that was opened up via another piece’s move. (also "Discovery")

Discovered Check    A discovered attack where the discovered piece also makes a check.

Discovery                   See Discovered Attack

Domination               1) When a knight or bishop (or any piece) dominates another, by guarding all it's potential moves (see Muller's article)
                                     2) (Dan) when a move, compared to another, has all pros and no cons

Double Attack Making a move which attacks two (or more) pieces by a the moved piece (most double attacks are also considered "forks")

Double Blunder   One side makes a bad mistake and his opponent doesn't take advantage (misses the opportunity)

Double Check           A discovered check where both the discovering and discovered piece both deliver check. In that case, the opposing king must move.

Double Threat A move that creates two (or more) threats, e.g. a direct attack combined with a discovered attack, or an attack on a piece while simultaneously threatening checkmate. This differ from a double attack in that both threats do not have to be attacks, nor do both threats have to be from the same piece.

Double Whammy     A type of problem where you make two pieces moves in a row for White and leave Black in a legal checkmate. The first move may not be check. See Jeff Coakley's Winning Chess Puzzles for Kids, Vol II

Doubled Pawns      Two pawns of the same color on the same file as a result of a capture

Doubled Rooks       Two Rooks forming a battery on a rank or file.

Draw                           NOT “tie” - Any game that ends without either player winning, e.g. stalemate, lack of mating material, 50-move rule, agreed, etc. Usually worth 1/2 point to each player

Drawn An evaluation of a position, usually in the endgame, that says with best play for both sides the game should end in a draw.

Dynamics (Dynamic analysis) - the aspect of chess that involves moving the pieces to see what might happen and/or evaluate, usually assuming best moves. As opposed to "statics".

Elbow See outflank

En Passant               Capturing a pawn that moved 2 spaces with a pawn that could have captured it if it had only moved 1 space, on the next turn only.

En Prise                   "In take" - able to be captured for free. A piece is en prise if it can be captured but is not guarded. Pronounced "aan-preez"

Endgame                  The final part of the game where the king should come out and fight (with fewer pieces left on the board). One definition of the endgame is when the "Reinfeld" values of the non-pawns (1-3-3-5-9) adds up to 13 or less for each side.

Engine A software program that inputs positions and outputs moves and evaluations, usually using the UCI convention.

Equalize To make the chances in the game equal. For example, in the opening White moves first so Black usually tries to equalize White's advantage.

Equilibrium (Dan) A position is in "equilibrium" when the captures/saves for each player are balanced. For example in the complicated Counting situation where there are 2 desperado pieces, if both can either be captured or saved, that's equilibrium & material balance stays the same (i.e., if one side was ahead by a certain amount of material, they will stay that far ahead. If material was even at equilibrium, it will stay even).

Evaluation Part of the thought process performed at analysis nodes (positions) to determine "Who stands better, how much, and why?" Computers
express evaluation in pawns (e.g. +1.89 means White stands almost 2 pawns better); older books use symbols like +/= (White is a little better)
* Static Evaluation: Evaluating the position on the current board position using only static features and not "moving the pieces", taking into account issues like king safety, piece activity, pawn structure, but not even who's move it is
* Dynamic Evaluation - evaluation based on what would happen if both sides make the best moves - this is the normal kind of evaluation that an engine would make (and the one a human should usually rely upon)

Exact Endgame A deep endgame position that occurse frequently in games and thus is featured in endgame encyclopedias and texts. Earlier endgame positions with more pieces that are unique to the game played can be considered "practical" or "inexact" endgames

Exchange (the)        Trading a Bishop or Knight for a Rook is winning the Exchange. Losing a Rook for a Bishop or Knight is losing the Exchange. NOT the same as trading pieces.

Expert                      A title granted to someone who has achieved a US Chess Federation established rating between 2000 and 2199

Feasible & Effective - (Silman) For a plan to be strongly considered, it must be both feasible (likely to be accomplished) & effective (does something positive which cannot (easily) be stopped once accomplished)

FEN "Forsyth–Edwards Notation (FEN) is a standard notation for describing a particular board position of a chess game. The purpose of FEN is to provide all the necessary information to restart a game from a particular position" (from Wikipedia)

Fianchetto To develop a Bishop onto a long diagonal by moving a knight-pawn one square then playing Bb2 or Bg2 for White; Bb7 or Bg7 for Black.

FIDE International Chess Federation

FIDE Master           (FM) Someone with the International Chess Title, usually for players rated 2300+ FIDE (but not yet an IM or GM)

Fifty-Move Rule     A type of draw where both players make 50 moves consecutively without either player advancing a pawn or making a capture.

File                           The rows of a chessboard going up and down, lettered a-h (lower case), with “a” always on White’s left (and Black’s right)

Fish                          A weak player; see patzer.

Five Minute/Blitz   A game where each player has five minutes to make all his moves. Blitz can also be any fast game.

Fixed Pawn Structure A position where multiple adjacent pawns cannot move, primarily because an opponent pawn is directly in front (Kmoch: "Ram"), e.g. White d4/e5 vs. Black d5/e6. A position with fixed pawns across most of the board is a blocked position.

Flag                         The part of an analog clock that rises as the minute hand nears the hour & falls at the hour. To "flag" someone is to call them on a time forfeit.

Flexibility               The capability of a piece or entire army to do multiple good things. A lack of flexibility is rigid (and "brittle") and generally very bad.

Floobly                    (Dan) Something which allows a player to suddenly win/draw despite his opponent's easily won/drawn position, e.g. overlooking a checkmate, stalemate, winning on time.

Focal point A square which is the target of attack(s). The book The Art of Attack by Vukovic has a chapter on focal points.

Fool’s Mate             A mate by Black on the 2nd move of the game. Anything similar to 1. f3? e5 2. g4?? Qh4# (e.g., White's first move could be 1.f4, etc)

Forcing moves Checks, captures, and threats or, more specifically, checks, threats of mate, captures, and other threats in descending order of "forcedness"

Forfeit 2 Definitions, depending upon context
                                            1) When you are expected to play in an event, but they don’t show up for their game (which is therefore not rated), or
                                            2) When someone loses on time, a “time forfeit” (which is rated like any other loss)

Fork A double attack, usually by a Knight or Pawn (thus forming a pattern like a “fork” in the road).

Fortress An endgame position where the side with inferior material situates his pieces so they can shuffle back and forth and the superior side cannot make progress, allowing the inferior side to draw.

Fritz A popular and very strong chess engine.

Front End Software using a graphical user interface to allow a human to play chess with a board, which uses an interface (almost always UCI) to communicate with an engine. For example, if you download the engine Stockfish, you need a "front end" to communicate with it.

Gambit Sacrificing material (usually a pawn) in the opening for a lead in development, open lines, and/or attacking chances.

Global Mobility (Dan) See Mobility.

Goal Something you are trying to achieve, e.g. the 3 goals of the opening are to 1) Quickly, efficiently, and safely activate all your pieces, 2) Get some control of the center, and 3) Place the king (usually through castling) in an area that is relatively safe for the middlegame.

Going to Sleep (GTS) (Dan) GTS in the endgame means creating a position where the opponent can't do anything, no matter how many tempos he/she has, and thus you can take time & make the needed progress. For example, with Q&K vs K&P, putting the queen in front of the pawn.

Grandmaster         (GM)   Someone with the highest International chess title as granted by FIDE

Hand-Waving        (Dan) - When you erroneously use general principles to decide upon a move in an analytical position when only careful analysis is required instead.

Hanging Pawns Two pawns side-by-side on the fourth rank (5th for Black) with no pawns of the same color on adjacent files, and both on semi-open files.
(e.g. Black pawns on c5-d5 with no Black b or e-pawns, and no White pawns on the c or d-files)

Hanging Piece   A piece that is not defended, especially one that is exposed and easily attacked. Exception: defending a king has no meaning so a king cannot be "hanging". Also called "loose piece".

Having a Better Idea - (Dan) - When an adult knows a principle and purposely ignores it and makes a move that goes against that principle because "...he has a better idea than what Lasker, Steinitz, Capablanca, Fischer, and Kasparov recommend..."

Helpmate                A type of problem where Black moves first and cooperates with White to checkmate Black in a fixed number of moves.

Hole A weak square on the opponent's side of the board.

Hook and Ladder Trick See "Ladder Trick"

Hope Chess          (Dan) When you make a move without considering whether a possible opponent reply of a check, capture, or threat can be met on your following move.
                                      My use of Hope Chess was NOT supposed to cover these other "Hope" possibilities:
                                            1) When you make a threat and hope your opponent does not see it,
                                            2) When you make a bad move and hope your opponent does not take advantage of it, nor
                                            3) You make an unanalyzed move quickly and hope the move/idea/maneuver works anyway, etc

Horse A beginner's word for a knight (worse: "He took my horsey!")

Houdini The highest rated computer engine 2011-2012

Hustler Someone who plays offhand games for money. Some hustlers may play intentionally poorly to lure the customer into raising the stakes.

Hydra   A multiprocessor, hardware-based chess program. Very strong. Successor to Deep Blue. Now defunct

ICC see Internet Chess Club

Illegal Move             A move that either a) Moves a piece in an illegal manner, or 2) Results in an illegal position, such as leaving the moving player's king in check at the end of the move. An illegal move usually requires pushing the clock; before that it's usually just touch move.

Inadequately guarded piece - A piece that is attacked, but is only guarded as many times as it is attacked. Inadequately guarded pieces may be subject to double attacks and double threats in much the same way that unguarded ("loose", "hanging") pieces can. Also known as inadequately protected or inadequately defended or barely adequetely guarded.

Increment                Time (in seconds) added to your clock for each move. For example, in the Team4545 League the time control is "45 45" meaning you get 45 minutes for the game plus 45 seconds added for each move. As opposed to time-delay

Indirect attack An attack by a fast piece (queen, rook, or bishop) through another piece of the same color that moves in the same direction, but the fast piece cannot make the first capture due to the other piece, e.g. White Bg2 & pawn e4 both attack a Black piece on d5, but the bishop attack is indirect.

Indirect attacker (defender)  A long-range attacker (queen, rook, bishop) that is behind a similarly moving attacker along the same line that can also attack/defend a square on that line. For example, a queen on c2 and a bishop on d3 can attack h7 twice with the queen the indirect attacker. In Gainnatos' book Everyone's First Chess Workbook he calls this an X-Ray attack (normally X-Ray is synonymous with skewer).

Initiative                    When your opponent is constantly responding to your forcing moves (checks, captures, and threats). GM Sokolov's interesting, and similar, definition is "When your opponent is more worried about your threats than busy creating his own."

Insufficient Losing Chances - A USCF draw rule where a player with less than two minutes remaining on an analog clock may claim a draw if he thinks he is clearly not losing but is in danger of losing on time. The TD has several options on how to rule, depending on the position. A common ruling is to exchange the analog clock for a time delay clock, but giving the claiming player half of his remaining time.

Interference A fairly rare tactical device where an opposing piece is forced to go to a square where it interferes/prevents/blocks the defensive capabilities of other pieces. These "other pieces" are almost always a bishop, rook, or queen.

International Master   (IM) - Someone with the second highest International Chess Title (next to GM)

Internet Chess Club (ICC) - a leading chess server; owner of Chess.FM; www.chessclub.com

Island See "pawn island.

Isolated Pawns Pawns that have no other pawns of the same color on adjacent files.

J'Adoube French. Means "I adjust" - used before touching a poorly placed piece to place it on the center of a square, or to fix a piece accidentally knocked over.

Kibitzer (originally Yiddish) A spectator who offers (usually) unwanted advice, sometimes incorrectly.

Killer Move A threat (such as mate in 1) that is so strong that it basically eliminates all the candidate moves that don't meet this threat.

King   The pieces which start the game on e1 and e8. Kings can move one square in any of the 8 directions. When a king is attacked it is in "check" and the players next move must get the king out of check. If that is impossible then it is checkmate and the players loses the game.

King of the Hill         The best candidate move you have found so far. The move which creates the position for which you are trying to find another move which creates a better one.

Kingside The files e though h (the files on the half of the board where the king is placed at the start of a game)

Kingside attack An attack on the kingside of the board, especially one that involves trying to checkmate the opponent's king.

Knight not Horse – the piece that moves like an “L”, and in Staunton design shows a horse's head.

Knight Tour To start a knight on a square (usually a corner square) and make 63 moves to visit all all 64 squares. Often performed blindfolded.

Komodo   The chess engine written by Don Dailey and GM Larry Kaufman; when Dailey passed away, Mark Lefler took over as programmer. In 2014- 2016 battled Stockfish for world #1. Version KomodoDragon will be in the TCEC final in 2022 vs Stockfish.

Ladder Trick Also known as the Hook and Ladder trick. Take this link for an explanation/sample.

Lasker's Rule   "If you see a good move, look for a better one" (because you are trying to find the best move you can in a reasonable amount of time).

LCZero Open source neural network based chess engine. One of the best chess engines (2022); architechture similar to AlphaZero.

Lever The situation where two opposing pawns are attacking each other (one square away diagonally).

LiChess A popular online chess server with many helpful services for players

Line Clearance Sacrificing material to open a diagonal, rank, and/or file to aide one or more fast moving (rook, queen, bishop) pieces. See also "Clearance"

Loose Piece   A piece that is not defended, especially one that is exposed and easily attacked. Exception: guarding a king has no meaning since a king can never be recaptured, so a king cannot be "loose". Also called "hanging piece".

Losing Move, (The) A move that, before made, the evaluation (assuming both sides play perfectly) is that the side moving is not losing, whereas after the move the evaluation is that the moving side is losing. It is possible there could be multiple losing moves in a game (the final one being the most significant), and losing moves can occur in a drawn game (where the winning side makes mistakes later & throws away the win).

LPDO                       Loose Pieces Drop Off (also known as "Nunn's Dictum"). This is a primary "Seed of Tactical Destruction".

LTD                          Local Tournament Director

Luft                         German for "air" - a square where the king can escape to prevent back-rank mate, created by moving a pawn.

Majority Having more pawns on a pawn island as opposed to the opponent's pawn island on the same files, e.g. "White has a queenside pawn majority because he has three pawns on the a,b, and c-files, while Black only has two pawns on the b and c-files" (the d-file is open).
Mobile: A mobile majority is one that can create a passed pawn (w/o help from pieces) vs the opposing pawn minority
Crippled: A crippled majority has weak pawns & cannot create a passed pawn vs the opposing pawn minority

Make it Work When you see a continuation in a critical position that might get you what you want (win, win material, mate, draw, etc) but at first it looks like the opponent can stop it, since the risk/reward is so high, take time to see if there is some way (maybe changing the move order) that you can achieve the desired result. In chess, this is called "trying to see if you can make it work".

Master                   Someone with a US Chess Federation rating between 2200 and 2399 is a national master (NM). There are higher levels of master, both national and international.

Match                      A series of games with a purpose (as opposed to "game" which is a single contest between two players):
                                    1) A set of games between two players, e.g. the "World Championship Match"
                                    2) A set of games between two chess teams; e.g. "Our club will play a match against their club"

Mate                       Short for "Checkmate"

Material                  Piece value - when you win a pawn, a piece, the Exchange, you are winning "material" On the average a Knight and Bishop are worth 3.5 pawns, a Rook 5.25 pawns, a Queen 10 pawns, and the King has a fighting value of about 4.25 pawns. Give yourself a bonus of 0.5 pawns if you have the advantage of the Bishop pair. (Value of the pieces courtesy of GM Larry Kaufman)

Mating Material   Enough material to checkmate a king by force: queen; rook, 2 bishops, bishop and knight, or pawn (can become queen). Two knights can legally mate but cannot force mate.

Middlegame The part of the game after the opening and before the endgame. The middlegame usually features a large number of pieces for both sides in conflict.

Minority attack   An attack with fewer pawns against a local majority. This is especially applied to the "Carlsbad" pawn structure (1.d4 d5 2.c4 e6 3.cxd5 exd5) where White can later push his a and b-pawns.

Mobile Majority Having a majority of pawns in one area of the board which can, without help of the other pieces, create a passed pawn

Mobility                 (Dan) The number of moves a piece has. The sub-types:
     1) Potential mobility - the number of moves a piece has from a given square on an empty board. A queen's potential mobility on e4 is 27.
                                    2) Actual mobility - the number of moves a piece has in a any given position. e.g. In the initial setup, each knight's actual mobility is 2.
                                    3) Global mobility - the number of future squares a piece can land upon in any given position. e.g. A bishop's global mobility is only 32

MCO                      Modern Chess Openings. A classic opening encyclopedia now in its 15th edition.

Monster               (Dan) A piece which is worth considerably more than that piece's normal average value. e.g. "That knight is a monster!"

Motif                     A basic type of tactic, e.g. pin, skewer, double attack, discovered attack, removal-of-the-guard, etc. Sometimes used as "tactical device"

NCO Nunn's Chess Openings. A competitor to MCO

Negative Move (Dan) A move where the mover is not in zugzwang, but if they had passed instead of making the move, their position would have been better. The way to test this is to use an engine and to note the evaluation of the position after making a move. Then retract that move so it is the position before the move was played, and then tell the engine it was the other player's move. If the first evaluation after the player's move is less than the evaluation the engine gives if it instead been the opponent's move, it is a "negative move" (the mover would have been better off "passing" than making the move they did. If the mover is in zugzwang, by definition they would be better off passing so that's excluded.

Non-rated A game, section, or event that will not be submitted for a rating. While often called an "unrated" section, that's confusing as an "unrated" section is one consisting of currently unrated players (those who have not yet earned a rating) but an unrated section is usually rated so the players can obtain a rating. See "unrated".

Notation              The recorded moves of a game. Note that the verb form is not to "notate" a game - you record it.

Novice Nook      My multi-award-winning column at Chess Cafe on how to improve at chess. Not just for novices!

NTD                      National Tournament Director

Null Move Hypothesis A thought process method where you assume you make no move in reply to your opponent's move, so that you can see what he could do next move if you did not move at all. This is an excellent method for finding threats generated from the opponent's previous move.

Open File A file containing no pawns (of either color)

Open Game         A game with multiple open files, especially the d and e-files. Alternately, a game that begins 1.e4 e5.

Opening The initial part of a chess game, usually lasting until all (or almost all) of the non-pawns are activated.

Openings Sets of moves that can be played from the initial position of the game, e.g. 1.e4 e5 2.Nf3 Nc6 3.Bb5 is the Ruy Lopez Opening. There are too many to be each named on this Chess Definitions page, but here is a link to the Chess Openings Wikipedia page.

Outflank A term used in a king & pawn endgame where one king can use zugzwang to force another king away from a defended pawn. For example FEN 8/8/8/8/2k1p3/4P3/2K5/8 w KQkq - 0 1 White to play 1.Kd2 Kb3 & Black outflanks White's king. Often called "elbowing" or "shouldering"

Outpost                A piece guarded in a hole (a weak square on the opponent's side of the board).

Overloaded piece See "Overworked piece"

Overpreparation   (Dan) Taking (wasting) tempos to continue to prepare a move which, if played immediately, would be safe and reasonable anyway.

Overprotected (Nimzovich) - a piece that is guarded more times than it is attacked, thus effectively freeing some of the defenders. It also removes the possibilities of tactics against a inadequately guarded piece.

Overworked piece A piece that is guarding multiple other pieces that are attacked. Thus when one of them is captured and the overworked piece recaptures, it is no longer able to guard the other piece(s), thus removing their guard. Also called "overloaded piece"

Patzer   A weak chess player; also called a "fish" (as in the big fish eat the little fish)

Pawn                     The weakest and most prevalent chess piece; can promote when reaching the 8th rank to another piece, other than a king. Moves ahead one square (two on the first move), but can only capture one square diagonally. See "en passant"

Pawn Break See "break move"

Pawn Chain         A series of pawns on contiguous files, usually where most of the pawns protecting at least one other (see "Pawn island")

Pawn Grabber     A player who likes to take pawns even if the resulting gain may be marginal or even negative. If badly negative see "Poisoned Pawn"

Pawn Island         A series of pawns of the same color on contiguous files; unlike pawn chain, there is no connotation that any pawns need protect each other.

Pawn Storm A sequence of moves where one player pushes multiple pawns in the same section of the board (usually directed at the opponent's king)

Pawn structure    How the pawns for one side are currently placed on the board.

Penetration When a piece, often a rook or king, can safely move deep into the opposing side of the board, with subsequent threats.

Phases of the game The opening, middlegame, and endgame

Piece                      3 Definitions, depending upon context:
1. All the chess men, as in “Get all the pieces out of the bag”
2.The non-pawns, as in “You have to develop all your pieces”
3. When discussing material, a bishop or knight, as in “I am up (ahead) a piece”

Piece Value The value a player assigns to each piece to decide whether to trade, or how much it can fight (see "Reinfeld Values" for basic piece values and The Evaluation of Material Imbalances for advanced values)

Pin                          An attack by a Rook, Bishop, or Queen, on a piece that cannot/should not move because a piece behind the attacked piece along the line of attack is worth even more. (See also: Sneaky Pin)
1) Absolute pin: If the piece behind is a King, this is an “absolute” pin and the piece is not allowed to move, or it would put the King into check, which is illegal.
2) Relative pin: a pin where the higher valued piece behind the pinned piece is not a king, so the pinned piece can legally move.

Playing Chess Backward (Dan) - Taking too much time on developing moves, and then when the position gets complicated, playing too fast. In other words, playing slowly on non-critical moves and playing quickly on critical moves.

Playing Strength  The currently established ability of a player. If a rating were perfect, it would match the playing strength.

Ply                            A half-move, or the move of one player. When both players move, that is two ply, or one full move.

Points A hypothetical evaluation quantity where 1 pawn = 1 point. Usually engine evaluations are in centipawns (e.g 1.83 pawn advantage); that's the equivalent of the same number of points. (Note: Dan much prefers "pawns" but "points" has its advocates & some acceptable logic behind it)

Poisoned Pawn    A pawn that if taken will lead to detrimental play, such as loss of material.

Potential Mobility  (Dan) See Mobility

Principle A saying/guideline/heuristic that suggests a way of doing something, doing it better, more efficiently, etc. (as opposed to a goal)
* Strong Principle (Dan) A chess principle that has fewer exceptions and is closer to a rule (e.g. a strong principle in the opening is to "activate your rook by placing it on the file where the opponent has activated his queen."
* Important Principle (Dan) A chess principle that occurs frequently (so is good to know) or one that when broken can cause large harm (e.g. the most important principle in the opening is to "move every piece once before you move any piece twice unless there's a tactic".

Promote                  What a pawn does that reaches the other side of the board. The moving player replaces it with a Queen, Rook, Bishop, or Knight on the promoting square. So you can have nine Queens, maximum.

PSCF                       PA State Chess Federation

Pseudo-sacrifice    A move which gives up material but involves no risk since the player making the move will get back or the material or more (or mate) by force in the next few moves. Many basic combinations start with pseudo-sacrifices, which is why a player cannot reject a candidate move just because it gives up material on the initial sequence. Also known as a sham sacrifice.

Purposeful Error    (Dan ) A bad move that violates a principle that was already known by the player. See Accidental Error

Putting the Question to the Bishop - If a bishop makes a move like Bg5/b5/b4/g4 to attack/pin a knight, playing ...h6, ...a6, ...a3, or h3 respectively to attack the bishop and force it to declare it's intentions.

PV                              Principal Variation – the predicted best moves for both sides (usually used in conjunction with computer analysis).

Queenside The files a though d (the files on the half of the board where the queen is placed at the start of a game)

Queenside majority Having more pawns than the opponent on the queenside.

Quick Chess           Chess played at a fast time control; for USCF this is usually 5-29 minutes for a game.

Quiescence A position reached in analysis where there are no further forcing moves (checks, captures, or threats) that are likely to change the evaluation of the position. One ideally wants to reach a quiescent position before evaluating

Quiescence Error A common error (mostly made by lower rated players) where a player stops analyzing and evaluates a position as "quiet" when there are still further forcing moves which would likely (or will) change that evaluation

Race chess             (Dan) Chess played without an increment or time delay (can deteriorate into a position where whoever moves faster wins)

Ram                          A pawn of each color fixed against each other on the same file so that neither can move, e.g. White pawn e4, Black pawn e5 (Kmoch: Pawn Power in Chess)

Rank                        The rows of a chessboard going sideways, numbered 1st-8th starting from White’s side as 1st

Ranking The ordinal place occupied by a player in a particular list, most commonly a specific rating list. For example, see the Live Chess Ratings list for the FIDE rankings (e.g. "Top 100 Classical time control")

Rapid Chess            A game where each player (usually) has 30 minutes (often 25 5) to make all his moves. Also known as "Action Chess"

Rating                      A quantitative measure of skill.  USCF Ratings are based on a formula originally postulated by Dr. Arpad Elo, and range from roughly 100 for beginners to 2800 for World Champions to 3600 for the top computers. Ratings are relative, not absolute, depending upon the population being rated, so a 1700 rating on Chess.com is not the same strength as 1700 on LiChess or USCF or FIDE.

Recapture To capture back after a capture has been made. Usually it is made in a fair trade to keep the material balance the same, e.g. "He captured my bishop with his bishop, so I recaptured his bishop."

Record                    To write down the moves of a game (verb). The noun is notation. Note that there is no chess verb "notate"

Real Chess            (Dan) For every move you consider whether a possible opponent reply of a check, capture, or threat can be met.

Refusal Chess A variant where the opponent may 1) accept a chess move or 2) refuse it & the opponent makes another move. If the first move is refused, the second move must be accepted: eg 1.e4 e5 2.Qf3 Nc6 3.Qxf7+ Kxf7??? ("refuse" was forced) White refuses, and Black is mated!

Refutation/Refute a) In the opening, a new move that makes a formerly viable line not as good. For example, 11.Qe2! is a refutation of that line.
b) In analysis or a combination, the defensive move that makes the offensive idea not work, e.g. "That sacrifice is dangerous, but if Black finds 37...Qb8! that refutes the line.

Registration           The time period before an event where players can sign up and play. To do so before that by phone, mail, etc. is "pre-registration".

Reinfeld Values The integer-based beginner-taught values of the pieces: pawn=1, bishop=knight=3, rook=5, queen=9. I named these after prolific American author Fred Reinfeld, who wrote most of the American beginner books in the mid-20th century.

Removal of the Guard - A tactical motif where the defender is captured or forced to move so that it is no longer defending. Usually seen in the form of Deflection or Overworked Piece. Sometimes called "Removing the defender"

Removing the Defender See "Removal of the guard".

Resigns                  When you purposely turn down your King or say “I resign” – the game is over and you lose. Note that shaking hands does not end a game.

Retained Image    The analytical error that occurs deep in a line where a player visualizes a piece as still on a specific square, when in earlier moves of that visualized line it had moved off that square.

Rook Lift Lifting a rook from the first rank (8th rank for Black) up to another rank that's fairly clear so the rook can further move sideways and become more active. For example, a rook on a1 can be "rook lifted" vis 1.a4 and 2.Ra3 intending later moves like Ra3-g3 or Ra3-h3.

Round                     The game number in a tournament, e.g. I have two wins and one loss and now am going to play round four. A tournament usually has a fixed number of rounds.

Round Robin         A system of pairing players where everyone in the same (small) section plays everyone else. Unlike a swiss system, this type of tournament calls for some level of commitment on the part of the players to attempt to complete all their games. The number of rounds in a single round robin is the number of players minus one.

Rut                           When a player is unable to improve or raise his rating despite consistent effort.

Rybka                     The best PC-based chess playing program in 2006-10.

Sacrifice To intentionally give up material for some potentially greater reward, either short term or long-term. If there is no forcing continuation that immediately gets the reward (usually more material or checkmate), that is a "real sacrifice". If the reward is immediate and obvious, that is a pseudo-sacrifice or sham-sacrifice.

Sandbagger          Someone who purposely keeps his rating low in order to qualify for easier sections and a better chance to win money.

Sanity Check A final part of the thought process used by beginners to ask (before finally making a move): "Is this move I am about to do just crazy? Can my opponent just mate me to take something for free?" A sanity check is only used by lower rated players who play "Hope Chess" and are prone to these type of errors; stronger players with a good thought process would have eliminated a crazy move much earlier in the process.

Scholar’s Mate      To mate on f7 (or, for Black, f2) with a Queen or a Bishop in 4 moves – usually a very bad thing to try. When teaching about this, Dan calls this “Dumb and Dumber”.

Section                    A part of a chess tournament where the players are paired together. Sections may be divided by rating class, scholastic vs. non-scholastic, rated vs. unrated, Scholastic Level, etc.

Seeds of Tactical Destruction    (Dan) Aspects of a position that might allow the opponent to play a tactic, e.g. loose pieces, weak back rank, vulnerable king, pieces along a geometric line, overworked pieces, etc.

Selfmate (Wikipedia:) "A selfmate is a chess problem in which White, moving first, must force Black to deliver checkmate within a specified number of moves against their will."

Semi-open File      A file with only pawns of the opponent. A semi-open game is one where both sides have semi-open (but not open) files.

Semi-stalemate     A K&P endgame technique where you "stalemate" an opponent's king (take away all its moves) and force him to make suicidal pawn moves.

Senior Master        Someone with a US Chess Federation rating over 2399

Series Mover (Wikipedia:)

Seriesmate: a directmate with White playing a series of moves without reply to checkmate Black (the seriesmover analogue to the directmate).
Serieshelpmate: a helpmate in which Black plays a series of moves without reply after which White plays one move to checkmate Black (the seriesmover analogue to the helpmate).
Seriesselfmate: a selfmate in which White plays a series of moves leading to a position in which Black is forced to give mate (the seriesmover analogue to the selfmate).
Seriesreflexmate: a reflexmate in which White plays a series of moves leading to a position in which Black can, and therefore must, give mate. Further, White is obliged to mate whenever he can, therefore he has to avoid in his series of moves a position in which he would have mating possibility (the seriesmover analogue to the reflexmate).

Sham sacrifice      See pseudo-sacrifice

Shot An unexpectted, strong move, i.e. "I thouight I was winning but my opponent found a shot that forced a draw."

Shoulder    See Outflank

Silly Threat   A threat that is not only easy to meet, but one that weakens your position when met. (Note: Lower rated players are encouraged to make silly threats when other low rated players miss them & allow a tactic, but to become an intermediate you have to stop making them.)

Simplify To trade pieces into a position with fewer pieces, preferably in an advantageous way. This is different than "Keep it Simple" which means to avoid complications.

Simultaneous Exhibition Also called "Simul" - One player plays multiple players at the same time. If the games are not played contiguously but instead a clock is used on each board, that is a "clock-simul"

Skewer/ X-ray        Tactical Motif: An inside-out pin. A move that attacks a piece of value, and there is a piece behind it along the line of attack of equal or lesser value that will be attacked anyway if the attacked piece moves.
Note: In Giannatos' Everyone's First Chess Workbook he uses "X-Ray" to mean "to guard through another like-moving piece"

Skittles                     Chess for fun or chess without a clock; A skittles room is where you go and play for fun while waiting for your next formal pairing.

Slow chess             Chess played at long enough time controls where good moves are generally more important than the time remaining. Usually at least 30 minutes per side.

Slump                      When a player consistently plays below his normal average playing strength

Sneaky Pin             Taking advantage of the squares that a pinned piece is not guarding (Hertan)

Space The concept of how much room the pieces have, measured in various ways almost always involving the pawn structure (a position without pawns generally would not use space as a concept). One measure would be the distance behind the pawn structure (to the back rank or the pawns' initial rank). A primary goal or purpose of space would be to give the pieces more mobility/activity.

Stalemate               When the player to move isn’t in check, but none of his pieces can move. This is a type of draw (not all draws are stalemates!)

Statics The aspects of the game that can be observed/evaluated by just looking at the board and without moving the pieces, e.g. open & semi-open files, weak squares, material count, weak and strong pawns, good and bad bishops, etc

Stockfish The highest rated digital-based engine in 2018 (Neural net Alpha Zero beat it in a match 2017)

STD                         Senior Tournament Director

Study Book (Dan) A Player's personalized study book is one that contains positions where they made errors that are worthy of study so as to not repeat. Typically below a position (showing which side is to move) can be 1) What the player did, 2) Why it was wrong, and 3) What they could have done.
A personalized study book can be used like a puzzle book so a player can see/study actual mistakes & help minimize them in the future.

Sudden Death      A time control period where all the moves have to be played within a certain amount of time (on that player’s clock).

Swindle                  A successful risk taken when a player is losing and purposely does not play the best move in the hopes that the opponent will make a mistake, and then that happens. A swindle sets a "trap" by making a less-than-optimum move to complicate the position.

Swiss-Sys             A software program to pair tournaments and provide tournament information

Swiss System      A system of pairing tournaments whereby players are paired against other players who are doing about as well as they are. Wherever possible, players get about an equal number of games with Black and White, and will not play the same opponent twice.

Switcheroo           A type of problem where you must switch ANY two pieces on the board and leave Black in a legal checkmate. Switching pawns to the 1st or 8th rank is not allowed. See Jeff Coakley's Winning Chess Puzzles for Kids books or his column "The Puzzling Side of Chess"

TCEC Top Chess Engine Championship - A web-based organization/competition that runs the most recognized computer chess (engine) events.

TD                          Tournament Director (internationally this is an "arbiter")

t/d                           Time delay - the amount of time a digital clock waits before your official time begins decrementing. Usually this is 5 seconds for over-the-board US Chess Federation play. This differs from an increment, which adds time to your clock.

Tabiya                   Arabic word originally meaning the opening setup of pieces, but now more commonly used to mean the standard moves of any opening, i.e. the real game starts after the players play the tabiya.

Tablebase            A database containing all positions with N or more pieces on the board and the result of that position with perfect play (with either side to move). N is currently 7 but N=6 is widely available.

Tactical Device   A tactical idea or set of ideas that can be used in multiple positions. Combining tactical ideas in a similar way in different positions to achieve one or more goals (including the tactical goals of winning material or checkmate). See "motif"

Tactical Justification Any tactics necessary to show that a move is safe. Usually this means that, at first glance, the move may not look safe, but its safety is ensured by this tactic (or sequence of moves showing what happens if the opponent tries to win/maintain material).

Tactical Vision    The ability to spot basic safety issues (motifs like pins, double attacks, removal of the guard, and Counting) when first analyzing a position

Tactics                  A forcing set of moves that involves piece safety and checkmating (A defensive tactic prevents these). These include:
      1) En Prise (can take a piece for free)
      2) Counting (is each piece safe from potential capturing sequences?)
      3) Other Motifs (pins, double attacks, removal of the guard, etc.)
      4) Non-sacrificial combinations of motifs
      5 Sacrificial combinations

Team Tournament  A tournament where the players play in rating order, first board against first, second against second, etc. The result is a team win, loss, or draw, depending on whether most of the players win or lose (or half of them do).

Team 4545           An online league which plays on the ICC and provides fun team play at the time control of 45 minutes with a 45 second increment

Technique Winning a won game. The ideas and maneuvers needed in a won position that would eventually lead to checkmate. A player is said to exhibit "good technique" if he wins a game where he was winning without allowing unnecessary counterplay or draw possibilities.

Tempo                  The (non-clock) “time” it takes for one of the players to make one move. A “turn”. (see "Winning a Tempo" and "Triangulation")

The Exchange    See "Exchange, the"

Threat                   A move which can win material, checkmate, or make progress next move if the opponent does not stop it.    Attacks on under-defended pieces are examples of a threat. (See also "Silly threat")

Three-Fold Repetition of Position       A type of draw where the same position is reached three times with the same player to move. Does not require the same moves and can occur at any point in the game.

Tie                          When two players or teams have the same score in a tournament or match. Not when a game is drawn.

Tiebreak               A method used for differentiating places between players with the same score. It is usually based on how well the opponents did in an event.

Tied Up A phrase meaning a piece (or pieces) are restricted because they have necessary duties, like guarding a piece. Tied up pieces have low flexibility.

Time Control       How much time one has for a game. "G" means all the moves and "SD" is sudden death, meaning that time control requires all the remaining moves must be played in a specified period. Also called "time limit"

In USCF over-the-board notation use a slash for moves/time: 40/2; SD/1 is 40 moves in 2 hrs followed by all moves in 1 more hr; G/30 all moves in 30 min
Online the two numbers (e.g. 60 5) are minutes per game and seconds incremented. So 60 5 is one hour for the game and 5 extra seconds per move.

Time Delay A digital clock is set to NOT run for the first N seconds on each move. Time is not added, as it is with a time increment.

Time Increment See "Increment"

Time Management   The skill of taking care of your clock time during a chess game, at two levels:
                                        1) To spend almost all your time for the game ("Macro time management") and
                                        2) Where you spend more time on moves that require it (critical, complicated, etc.) "Micro time management"

Touch Move         The rule that states:
1) If you purposely touch a piece you have to move it,
2) If you let go of a piece you have to leave it there, and
3) If you purposely displace an opponent’s piece, you have to take it.

Tournament See "chess tournament"

Trade                    To exchange one piece for another of the same or similar value. NOT the same as "the Exchange"

Trade or Retreat (Dan) - A common type of technique where the player who is winning offers a fair trade of pieces while moving the offering piece to a good square. Since the losing player does not normally wish to trade, he is left with the option of trading or allowing the offering piece to stay on the good square. Thus the defender must "trade or retreat".

Trap                      (Opening Trap) A known opening sequence where a player apparently follows good opening principles but the move is not tactically sound. Cambridge Springs trap: 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Nbd7 5.cxd5 exd5 6.Nxd5?? Superficially reasonable to grab the pawn when the f-knight is pinned, but... 6...Nxd5! 7.Bxd8 Bb4+ 8.Qd2 Kxd8 and Black will end up ahead a piece. (Compare: Blunder; Swindle)

Trebuchet   An endgame position king and pawn vs king and pawn where the four pieces align in a manner looking like the ancient trebuchet weapon (e.g. FEN 8/8/8/3Kp3/4Pk2/8/8/8 w KQkq - 0 1). It is a mutual zugzwang position where whoever is to move loses.

Triangulation Moving a piece (usually the king) three times in a "triangle" of squares to take an extra tempo while the opponent is unable to do so, and can only move back and forth. The idea is to create the same position with the opposite side to move (i.e., "losing a tempo"), for some type of advantage (e.g. the position wasn't winning with that player to move but would be winning if the opponent was in zugzwang & had to move)

Trigger One        (Dan) Finding a move such that there can't be a better one (thus triggering a player to make that move)

Trigger Two        (Dan) A reasonable amount of time to make a move, given the position, the time control, the times on the clock, and possibly the move number.

Two Bishops      Short for "The advantage of the two bishops" - See "Bishop Pair"

Two-way bishop   (Dan) - a bishop that is strong on both diagonals

UCI Universal Chess Interface - "an open communication protocol for chess engines to play games automatically, that is to communicate with other programs including Graphical User Interfaces" (Chess Programming Wiki)

Undermine (-ing) To remove the basis of a structure or strategy, e.g. "White undermined Black's plan to penetrate his rook to the 7th rank"

Underpromotion   When a pawn promotes, but the moving players chooses to get something other than a queen.

Unrated                An unrated player who has never played a rated game, or one whose rating has not yet become official. An unrated (or non-rated) game is one that will not be played for a rating. See "non-rated".

Unstoppable threat - a threat that cannot be met. Weak players allow unstoppable threats by playing Hope Chess, but even the best players resign when outplayed and faced with unstoppable threats.

USATE                 US Amateur Team East - one of the world's biggest team tournaments, held over President's Day weekend at the Hilton in Parsippany.

USCF                    United States Chess Federation

Visualization       The ability to keep track of where the pieces would have moved during lines of analysis. Humans use their imagination to visualize.

Wallchart             A more complete crosstable posted at events showing the player's name, rating, ID, opponents, color each round, and results. Wallcharts show an individual's score cumulatively; crosstables show each game's result

Weak square      A square which can no longer be guarded by a pawn.

Weakness 1) A weakness in a position is something wrong in the position that can be exploited, eg weak squares, dis-coordinated pieces, weak back rank.
2) A player's weakness is an area of the game where they either lack knowledge or make consistent mistakes, eg "weak in planning", "weak in the endgame", "makes quiescent errors", or "takes lower-rated players too lightly and plays too fast"

White The player who moves first in a game, usually with the lighter colored pieces.

Windmill A tactical device whereby a discovered check can be repeated as many times as required to win multiple pieces along a rank or file, usually with a rook doing the discovery and discovering a check by a bishop

Winning A position is winning if that side would win, assuming both sides play perfectly the remainder of the game. If one side's evaluation is superior, but not winning with best play, then that side is merely "better" but not winning. When the position is winning it is called a "won game".

Winning a Tempo In the endgame, these means losing (or gaining) a move to get the same position with the other side to move. This is often done to put the other side into zugzwang. In the opening, "winning a tempo" means making a developing move that attacks a piece of greater value, forcing that piece to move to a square that's no better, thus "wasting" a move. Since the one player makes good use of the move and the other player does not, the player making the useful move has said to "win a tempo".

Wise Adult Syndrome    (Dan ) A fast move made with plenty of time on the clock even though the move may be critical and careful analysis was required. Could be due to Hand-waving

Woodpusher      A weak chess player (He doesn't analyze; he just "pushes-wood" [pieces] around the board). Similar to one who plays by "hand-waving".

World Champion (WC) - the player who has won the official world championship event (tournament or match). Could be in a particular type, e.g. Junior or Women's World Champion, or a different speed like blitz or rapid WC.

Zone of protection -   (Dan) The area where a (passed) pawn can be adequately guarded & is safe; i.e., "Don't push a passed pawn past its zone of protection.

Zugzwang           When one side has to move, but any move is bad. Note: Some contend it is not true zugzwang unless the opponent could not win without this compulsion (in other words, if the player to move could pass but your opponent can still win then, although any move is bad, it is not a true zugzwang).
Mutual Zugzwang - an (endgame) position where the side who is NOT to move has the advantage. See "Trebuchet"

Zwischenzug      An in-between move. For example, after a capture, instead of re-capturing, you give a check first. Sometimes called an "intermezzo".

960 Chess            Also known as Fischer Random chess. A variant where the pieces are placed randomly on the back rank with certain rules such as bishops of opposite colors, king between rooks. There are 960 possible starting configurations.

Definitions

Services

Support