Glossary of Chess - A

A

Absolute pin

A pin against the king, called absolute because the pinned piece cannot legally move as it would expose the king to check. See relative pin.

Active

Describes a piece that is able to move to or control many squares. See also passive.

Adjournment

Suspension of a chess game with the intention to continue at a later occasion. Was once very common in high-level chess, often soon after the first time control, but the practice has been abandoned due to the advent of computer analysis. See Sealed move.

Adjudication

The process of a strong chess player (the adjudicator) deciding on the outcome of an unfinished game. This practice is now uncommon in over the board events, but does happen in online chess when one player refuses to continue after an adjournment.

Adjust or j'adoube (See Touch-move rule)

To adjust the position of a piece on its square without being required to move it. Adjustment can only be done when it is the player's move and the adjustment is preceded by saying "I adjust" or "j'adoube".

Advanced pawn

A pawn that is on the opponent's side of the board (the fifth rank or higher). An advanced pawn may be weak if it is overextended, lacking support and difficult to defend, or strong if it cramps the enemy by limiting mobility. An advanced passed pawn that threatens to promote can be especially strong.

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Alekhine's gun, as played in Alekhine vs. Nimzowitsch 1930

Alekhine's gun

A formation in which a queen backs up two rooks on the same file.

Algebraic notation

The standard way to record a chess game using alphanumeric coordinates for the squares.

Amateur

The distinction between professional and amateur is not very important in chess as amateurs may win prizes, accept appearance fees, and earn any title including World Champion. In the 19th century, "Amateur" was sometimes used in published game scores to conceal the name of the losing player in a Master vs. Amateur contest. It was thought to be impolite to use a player's name without permission, and the professional did not want to risk losing a customer. See also NN or N.N.

Analysis

Study of a position to determine best play for both sides.

Annotation

Commentary on a game using a combination of written comments, chess symbols or notation.

Announced mate

A practice, common in the nineteenth century, where one player would announce a sequence of moves, believed by him to constitute best play by both sides, that led to a forced checkmate for the announcing player in a specified number of moves (for example, "mate in five").

Antipositional

A move or a plan that is not in accordance with the principles of positional play. Antipositional is used to describe moves that are part of an incorrect plan rather than a mistake made when trying to follow a correct plan. Antipositional moves are often pawn moves; since pawns cannot move backwards to return to squares they have left, their advance often creates irreparable weaknesses.

Anti-Sicilian

An opening variation that White uses against the Sicilian Defense (1.e4 c5) other than the most common plan of 2.Nf3 followed by 3.d4 cxd4 4.Nxd4 (the Open Sicilian). Some Anti-Sicilians include the Alapin Variation (2.c3), Moscow Variation (2.Nf3 d6 3.Bb5+), Rossolimo Variation (2.Nf3 Nc6 3.Bb5), Grand Prix Attack (2.Nc3 Nc6 3.f4 g6 4.Nf3 Bg7 and now 5.Bc4 or 5.Bb5), Closed Sicilian (2.Nc3 followed by g3 and Bg2), Smith-Morra Gambit (2.d4 cxd4 3.c3), and Wing Gambit (2.b4).

Arbiter

See International Arbiter.

Armageddon chess

A game which White must win to win the match, but which Black only needs to draw to win the match. White has more time than Black: the discrepancy can vary; usually in FIDE World Championships, White has six minutes, while Black only has five, but in World Chess Championship 2012 the following time control is used: 5 minutes for White, 4 minutes for Black, plus 3 seconds increment from move 6. Typically used in playoff tie-breakers where shorter blitz games have not resolved the tie.

Artificial castling

Refers to a maneuver of several single moves by the king and a rook where they end up as if they had castled. Also known as "castling by hand".

Attack

An assault, either short-term (e.g., after 1.e4 Nf6, Black is attacking White's pawn on e4) or long-term, for example in the form of a sustained mating attack against the enemy king or a minority attack against the opponent's queenside pawn structure. See defence.

Attraction

If a player sacrifices minor or major pieces to expose the enemy king. For example, if the black king has castled and is on the g8-square, white may attempt to "attract" the king by using forcing moves such as Bxh7+, followed by Ng5+ etc.

Automaton

A self-operating chess-playing machine. Popular attractions in the 18th and 19th centuries, most of these devices were hoaxes under the control of a human player. The most famous chess-playing automaton was The Turk.