Glossary of Chess

S: Alternate notation for the knight piece. Used rather than the K, which is for King. From the German "Springer".
Sac: Short for sacrifice, usually used to describe a sacrifice for a mating attack.
Sacrifice: When one player voluntarily gives up material in return for an advantage such as space, development, or an attack. A sacrifice in the opening is called a gambit.
Sans voir: (from the French) See Blindfold chess.
Scholar's mate: A four-move checkmate (common among novices) in which White plays 1. e4, follows with Qh5 (or Qf3) and Bc4, and finishes with 4. Qxf7#.
Score: A record of the moves of a particular game, usually expressed in algebraic notation.
Score sheet: The sheet of paper used to record a game in process. During formal games, it is usual for both players to record the game using a score sheet.
Sealed move: Lengthy OTB games can be adjourned. To prevent unfair advantage, the players can agree on the next move being secretly recorded in a sealed envelope. Upon resumption, the arbiter makes the sealed move and the game continues. See also Adjournment.
Second: An assistant, often hired to help a player in preparation for and during a major match or tournament. The second assists the players in areas such as opening preparation. The second also assisted with adjournment analysis, before the practice of adjournments was abandoned in the 1990s.
Seesaw: See Windmill.
Semi-Open Game: A chess opening that begins with White playing 1.e4 and Black replying with a move other than 1...e5. Also called Half-open or Asymmetrical King Pawn openings. See also open game and closed game.
Semi-Closed Game: A chess opening that begins with White playing 1.d4 and Black replying with a move other than 1...d5. See also open game and closed game.
Sham sacrifice: An offer of material which is made at no risk, as acceptance would lead to the gain of equal or greater material or checkmate. This is in contrast to a true sacrifice in which the compensation is less tangible. Also called a pseudo-sacrifice.
Sharp: Risky, double-edged, highly tactical. Sharp can be used to describe moves, maneuvers, positions, and styles of play.
Simplification: A strategy of exchanging pieces of equal value. Simplification can be used defensively to reduce the size of an attacking force. It can also be used by a player with an advantage to amplify that advantage or reduce the opponent's counterplay. Simplification is also used as an attempt to obtain a draw, or as an attempt to gain an advantage by players who are strong in endgame play with simplified positions. Also liquidation and trading.
Simultaneous chess: A form of chess in which one (usually expert) player plays against several (usually novice) players simultaneously. Is often an exhibition.
Skewer: An attack to a valuable piece, compelling it to move to avoid capture and thus exposing a less valuable piece which can then be taken.
Skittles: A casual or "pick-up" game, usually played without a chess clock. At chess tournaments, a skittles room is where one goes to play for fun while waiting for the next formal game.
Smothered mate: A checkmate delivered by a knight in which the mated king is unable to move owing to it being surrounded (or smothered) by its own pieces. This could occur, for example, after 1.e4 Nc6 2.Ne2 Ne5, and now either 3.c3?? Nd3# or 3.g3?? Nf3#.
Sofia rules: In the tournament played by Sofia rules, players are not allowed to draw by agreement. They could have draws by stalemate, threefold repetition, fifty-move rule, or insufficient material. Other draws are only allowed if the arbiter declares the game reached a drawn position.
Solid: An adjective used to describe a move, opening, or manner of play that is characterized by minimal risk-taking and emphasis on quiet positional play rather than wild tactics.
Sound: Correct. A sound sacrifice has sufficient compensation, a sound opening or variation has no known refutation, and a sound composition has no cooks.
Space: The squares controlled by a player. A player controlling more squares than the other is said to have a spatial advantage. Effectively means much the same as mobility.
Spanish bishop: A White king bishop developed to the b5 square. This is characteristic of the Ruy Lopez, also known as the Spanish Opening.
Spite check: A harmless check given by a player who is about to be checkmated that serves no purpose other than to momentarily delay the defeat.
Squeeze: 1. Gradually increasing the pressure of a bind.; 2. Sometimes a synonym for zugzwang that is not a mutual zugzwang.
Stalemate: A position in which the player whose turn it is to move has no legal move and his king is not in check. A stalemate results in an immediate draw.
Staunton chess set: The standard design of chess pieces, required for use in competition.
Stem game: A stem game is the chess game featuring the first use of a particular opening variation. Sometimes, the player or the venue of the stem game is then used to refer to that opening.
Strategy: Evaluation of game positions and setting up goals and longer-term plans for future play, as opposed to a tactic which is a shorter-term plan typically consisting of a well-defined sequence of moves and their contingent moves from a given position in a game.
Strength: In context of a move, means a forceful or good move. In context of position, means having good winning chances. In context of a player, means a highly-rated player or one successful in tournaments. In context of a tournament, means one having a sizable number of strong players competing, such as Grandmasters. A "strong showing" refers to a player's high win ratio in a tournament. The opposite term is weakness.
Strongpoint: A "strongpoint defense" means an opening which defends and retains a central pawn (White: e4 or d4; Black: e5 or d5), as opposed to exchanging the pawn and relinquishing occupation of that central square. (More generically, a strongpoint can be any square heavily defended.)
Sudden death: The most straightforward time control for a chess game: each player has a fixed amount of time available to make all moves.
Swindle: A ruse by which a player in a losing position tricks his opponent, and thereby achieves a win or draw instead of the expected loss. It may also refer more generally to achieving a win or draw from a clearly losing position. See also cheapo.
Swiss tournament: This is a tournament that uses the Swiss system to determine player pairings. The basic idea is that every round each player is paired with an opponent with the same (or close to the same) score. The 33rd Chess Olympiad is an example of a Swiss tournament. See also Round-robin tournament.
Symmetry: A symmetrical position on the chessboard means the positions of one's pieces are exactly mirrored by the opponent's pieces. This most often occurs when Black mimics White's opening moves. Black is said to break symmetry when he makes a move no longer imitating White's move.