A chess glossary

"The meaning is the use" - WITTGENSTEIN

More than most of these pages, this represents work in progress, and particularly your corrections, additions, and examples in PGN are invited!

 I don't think it needs a search facility: it's not very long and you can use the one in your browser.

 I'm gradually adding examples: Example means I've got one, example? means I'd like one. Games in handouts are usually also in the Canon.

 I started this a long time ago when browsing through Tartakower and du Mont's 500 Master games of chess, mostly because they kept throwing in different terms for various sorts of sacrifices. If you know other good sources, please let me know!

  An international glossary is to be found in Hooper and Whyld's Companion.

Caveats: There is little or nothing from the problem world, nor from Euwe and Kramer (e.g. their classification of pawn structures), nor from Kmoch.

Credits: the rec.games.chess.* FAQ, books above.

Glossary and Acronyms:

- Example:
to take e.g. an offered pawn - Example: 1. e4 e5 2. f4 exf4 is the King's Gambit Accepted. Antonym: declined.
accumulation of advantages (accumulation theory):
an approach to positional play, seen in Steinitz, where one advantage is used to secure another, or at least is held while another is sought. Examples in the Strategy/Themes section of the Canon by Steinitz.
active defence:
defence involving some form of counterattacking method - either by attacking elsewhere, or by attacks against the opponents' attacking pieces. Example in the Defence section of the Canon.
to have more of a chessboard asset - material or positional (time, space, mobility, Pawn skeleton) Examples all over the Canon.
AI =
Artificial Intelligence
amaurosis scachistica:
chess blindness (oversight), described ironically as a disease by Dr. Tarrasch. There is a superb example from Krogius in the Errors section of the Canon.
usually an examination of variations Examples in the Analysis section of the Canon.
against good strategical principles, as opposed to being a tactical oversight; Fischer famously described the Winawer Variation as "anti-positional", as it gives up the good Bishop and weakens the King's-side.
artificial castling, or castling by hand:
to exchange positions of king and rook by other means than normal castling e.g. by playing Ke1-f2, Rh1-e1,Kf2-g1 as in the main line of the Benko Gambit.
artificial manoeuvre:
trying a bit too hard, or making an odd use of pieces. Simple examples might include blockading a pawn with a Q or developing the Rook by h2-h4 and Rh1-h3. Capablanca's style was the opposite of artificial - his games have a natural, graceful feel which is easy to recognise (but hard to do).
to move with a threat e.g. so that an opponent's piece may be taken; more generally, to move pieces towards e.g. the king's side in the hope of mate. Also used to describe some opening systems initiated by White, e.g. King's Indian Attack.
back rank:
the rank behind your Pawns. After castling the King's movement forward is often blocked by Pawns on the f,g and h files, and if the Rooks are played forwards you may fall into a back rank mate. In order to avoid this, players may create Luft (airhole) by a move like h2-h3. There are examples of back rank mates in the Tactics section of the Canon.
bad bishop:
a bishop hemmed in by its own pawns, on the same colour squares. Examples in the Bishops handout (and in the Canon).
Basic Chess Endings
British Chess Federation
Batsford Chess Openings
a grip on the position, usually held by Pawns, e.g. the Maroczy bind.
black (white) square weaknesses:
having holes on the black squares. Examples include Bernstein-Mieses and Znosko-Borovsky vs. Mackenzie in the Strategy/Themes section of the Canon.
black square complex:
a network of black squares. Examples include Bernstein-Mieses and Znosko-Borovsky vs. Mackenzie in the Strategy/Themes section of the Canon.
usually of pawns - a pawn may be blockaded by an enemy piece or pawn standing in front of it. The same effect may be achieved by good control of the square in front of it so that it would be taken without compensation if it advanced. example?
blockaded pawn:
a pawn where the square in front is occupied (or strongly controlled) by opposing pieces. An isolated pawn on c6 can be blockaded by Nc5; there are lots of examples in the Pawn mobility handout.
an oversight; the Tactics section of the Canon is full of them.
break (pawn break):
a Pawn move with the hope or intention of opening lines, particularly files. In blocked positions like the French Defence it's important to organise your own pawn break.
break-up sacrifice:
a sacrifice to disrupt the defences e.g. Bxh6, gxh6, an example of which can be found in the Attacking section of the Canon.
the breaching of an apparently secure formation, often with sacrifice of material, as in the Pillsbury-Lasker game in the French Defence.
building a bridge:
Nimzovitch's description of how to win the Lucena position (q.v.) in a Rook ending.
candidate move:
a move considered as a starting point in the analysis of variations. The term was made popular by Kotov's classic Think Like a GM, the first chapter of which has been very influential; there are some examples in theAnalysis section of the Canon.
a Pawn that may be promoted; also, a player in competition to become the challenger for the world championship(s). See tha game Marshall-Capablanca in the handout on Pawn mobility.
CC =
correspondence chess (also known as postal chess, although e-mail chess is catching up!)
to move pieces towards the centre - a good idea if there is no obvious alternative plan. Example in the Strategical Themes section of the Canon.
the central four squares e4/d4/e5/d5 or the sixteen squares including these and those next to them.
clearance sacrifice:
see vacating sacrifice
close game or closed opening:
often slow, partly blocked positions, often arising from e.g. 1. d4 d5, with locked chains of pawns. There are several examples discussed in the Pawn formations handout.
a forcing sequence involving threats (of capture, check and/or mate), probably involving a sacrifice. There are examples in the Tactics and Attacking sections of the Canon.
complementary sacrifice:
a sacrifice which follows up a previous sacrifice - e.g. the double bishop sacrifice Bxh7/Bxg7, or two others like Rxf6/Nxh7 (See Lasker-Bauer)
towards the centre
conjugate squares (coordinate squares):
squares on which Kings have the relation of distant opposition, possibly complicated by intervening Pawns of either colour example?
connected pawn:
a Pawn with a Pawn on an adjacent file; a group of connected pawns form a pawn island. There is a nice example from Capa in the handout On manoeuvres, and another from Karpov in the style section of the Canon.
consolidating manoeuvre:
to shore up a point e.g. Re8, Qe7, Nf6-d7 to protect e5.
control of centre:
the controlling influence of one side over the central squares. See the rules for openings, and the opening section and under centralisation sections in the Canon. The hypermoderns pointed out that need not mean its occupation.
a general term used to describe the way pieces work togther - for example, in an endgame, Q+N coordinate better than Q+B, a circumstance in which it is no disadvantage to have a Knight while the opponent has a Bishop (see minor exchange). There are some nice examples of coordination in the Strategy/Themes section of the Canon.
lack of mobility. See the examples on Space in Strategy/Themes section of the Canon.
a check in reply to a check, typical of Queen endings (See the second Nimzo game in the handout On Manoeuvres.)
to move away from the centre, often an anti-positional move. There are examples in the handouts on Bishops Italian Game.
a move which alters or makes certain the result of a game: a decisive move may make an advantageous position a winning one, a decisive error may lose the advantage, or the game. Examples are to be found in the handout on Planning, and Kotov's Think Like a GM.
to leave an offered pawn or piece, e.g. 1. e4 e5 2. f4 Bc5 is the King's Gambit Declined. Antonym: accept
a diversion, as in the model game Morphy-Meek.
decoy sacrifice:
a sacrifice to remove a piece, e.g. to play Ba5 when ...Qc7xa5 means that the K will lack an important defender (see decoy)
to move to defend against an threat, e.g. to protect a piece that is attacked; more generally, a period of the game where the player is meeting and anticipating threats during an attack. Also used for opening systems chosen by Black, e.g. King's Indian Defence. There is a section in the Canon on Defence.
to distract a piece or pawn away from a task [example?]
deflecting sacrifice:
a sacrifice to deflect a defending piece e.g. to play Re1-e4 to deflect a Black Qb4 away from attacking b2. example?
denuding sacrifice:
a sacrifice to strip away defending pawn shield e.g. Bxh6 from the Attack section of the Canon.
the bringing-out of pieces at the start of the game - one of the aims of the opening . Examples in the Openings Canon.
the chain of squares of the same colour running diagonally across the board: a1-h8 and a7-g1 are diagonals example?
diagonal mate:
mate where the decisive check is delivered along a diagonal, as in Fool's mate 1. g4 e5 2. f4 Qh4#
discovered attack:
to attack by moving a piece or pawn out of the way of a line-piece such as rook, bishop or queen. 1.e4 discovers an attack on b5 and h5. There are examples in the Tactics section of the Canon.
discovered check:
to deliver check by moving a piece or pawn out of the way of a line-piece such as rook, bishop or queen. There are examples in the Tactics section of the Canon.
separation of pieces or pawns example?
dislodging manoeuvre:
a move to upset a defensive formation example?
where pieces fail to protect key squares or each other, the opposite of coordination. See the booklet on Italian Game.
distant opposition:
Kings separated by more than one rank (or file) but which still have the relation of opposition e.g. Kings on g1 and g5. See also the booklet on King and pawn endings.
distant/outside passed Pawn:
a passed Pawn on the other side of the board from the defending King or other pieces - usually winning in a King and Pawn ending [example?]
diversionary sacrifice:
sacrifice in order to decoy [example?]
double (of Pawns):
to force enemy Pawns to become doubled, as in the booklet on Pawn mobility.
doubled Pawns:
Pawns on the same file, often one obstructing the other, as in the booklet on Pawn mobility.
double (of Rooks):
Rooks on the same file; if the Queen is also on that file the major pieces are tripled. We can see doubling in the handout on Rooks, tripling in the one on Pins.
double attack:
to attack two pieces at the same time with one move; 1.e4 attacks d5 and f5. Chernev and Reinfeld say that this is one of the two central themes of tactical play (the other being concentration of force). Lots of examples in the Tactics section of the Canon.
double Bishop sacrifice:
two complementary Bishop sacrifices, e.g. on g7 and h7, as in the famous game Lasker-Bauer.
double check:
check from two pieces at once, always obliging a King move. Examples in the Tactics section of the Canon.
double fianchetto:
both Bishops developed in fianchetto, as the Hypermodern Reti was fond of doing.
double Rook sacrifice:
typically to allow a Queen to play ...Qxa1+, K moves, Qxh1, hoping to decoy the Queen away from defence. The Immortal Game features such a sacrifice, included in the attacking section of the Canon.
DT =
Deep Thought
Deep Thought; next version
eccentric development:
moving a piece to an unusual square e.g. Ng1-h3.
Encylopedia of Chess Openings
elimination sacrifice:
a sacrifice to remove an important defender e.g. ...Rc8xNc3. Compare with examples of 'removing the guard' from the Tactics section of the Canon, which are without sacrifices.
rating using Prof. Arpad Elo's rating system
en prise:
in a position to be taken
a game where several pairs of pieces have been exchanged, probably including the Queens, and where play is concerned not with checkmate or tactics as much as with gaining, and promoting, Pawns. See Endgame Handouts.
equilibrium/balance of position:
an equal but not lifeless position is in balance or equilibrium; if this is not disturbed the correct result should be a draw. However, unduly slow or unduly rash moves may disturb the balance and give the opponent the advantage. See latitude of the draw.
a mistake in analysis or assessment; a gross oversight is called a blunder. There is a section on errors in the Canon.
exchange is used in two senses - to swap off for equal material, or unequal material. To lose the exchange usually means to lose rook for bishop. The minor exchange refers to the loss of bishop for knight, but this is not always a disadvantage. [example?]
extended fianchetto:
to fianchetto with e.g. b3 and Ba3. Also used for fianchetto with b4 and Bb2. [example?]
F-S II =
Fischer-Spassky match held Sept-Nov '92 (Fischer won 10-5)
fairy chess:
chess with newly invented pieces, usually seen in studies but can be played as a new game. [example?]
family check:
a check with other pieces attacked at the same time e.g. to play Nc7+ with Black Ke8, Ra8, Qd5. There is an example in Capablanca-Treybal in the handout On manoeuvres and in the Canon.
to develop a bishop to the long diagonal by e.g. b3 and Bb2.
Federation Internationale des Echecs
the columns of squares, e.g. a1-a8 is the a-file (Queen's Rook file)
obstructed or restrained: see the Pawn formations handout.
flank opening:
slower openings aiming at control of the centre rather than its occupation - for White, this includes the English (1.c4), Reti (1.Nf3), and Catalan (1.d4,2.c4,3.g3) openings. See the handout on the hypermoderns.
flight square:
a square available for a King to move to. If a King has no flight squares, a check may give mate. See my game against Terry GRAY in the Defence section of the Canon.
FM =
FIDE Master
force (noun):
loosely, material. Chernev anbd Reinfeld see this as the other great defining theme of tactical play. See the model game by Kasparov in the Canon.
to attack two pieces, usually with a knight e.g. Nf7 attacking Qd8 and Rh8. Examples in the Tactics section of the Canon.
a defensive blockade, keeping out the enemy forces, especially the King. One of the earliest known examples is the fortress White Kc1, Pd3, Re3 which can hold the draw against Black Kc8, Qd8. Try it!
usually to sacrifice a pawn in the opening to gain development. Examples in the Openings section of the Canon.
GM =
half-open file:
a file with pawns of only one colour. Look at the handouts on Rooks and, if you are brave, the Minority Attack section of the handout on Pawn mobility.
half-passed pawn:
30 minutes after Pawn o'clock. [example?]
a solid defensive arrangement with Pawns on the third rank e.g. Pb6,c5,d6,e6,g6, Bb7, Nbd7, Ngf6 and Be7 or Bg7. There is a comment on the potential of this formation under Nunn-Olafsson in the Planning section of the Canon, and an example game Webb-Hartston elsewhere in the Canon.
openings in the defensive front are called holes - usually holes cannot be defended by pawns. To play ...g6 creates a hole at h6. See Steinitz-Blackburne in the Strategical Themes section of the Canon.
the treatment of the opening by the Hypermodern school, a description given them by Tartakower; I wrote a little booklet on their treatment of the opening.
Internet Chess Server
see GM
IM =
International Master
intermediary manoeuvre:
an in-between move or apparent diversion from the main line of events. I read the term in the Tartakower-duMont book, in an annotation to the Tartakower-Capablanca game I encluded in the Tactics section of the Canon.
see Zwischenzug
Isolated Queen's Pawn
irruptive sacrifice:
to break into the defences with a sacrifice e.g. Bxh7+, of which there are examples in the Attacking section of the Canon.
Nimzovitch's term for an isolated pawn.
isolated pawn or isolani:
a pawn with no friendly pawns on the next-door files. There are always negative features, but may be compensating advantages - and these benefits are seen in the most positive light with an isolated Queen's Pawn. See the many examples in the Planning section of the Canon.
isolated Queen's Pawn:
an isolated pawn on d4 or d5 - here the compensating extra space and influence over the centre are at their maximum and can compensate for its weakness in the middle game. IQP positions often arise in the early middle-game from the QGD and Caro-Kann. See the many examples in the Planning section of the Canon.
Italian diagonal:
the diagonal a2-g8 dominated by Bc4 (or ...Bc5), the favoured development of the Italians of the Modenese school. See the booklet on Italian Game.
International Woman Master
King's Indian Attack. There is some commentary on this opening in relation to the Sicilian Defence here..
to offer advice as a spectator - a dangerous pastime.
King's Indian Defense. I based a session on this system once, and the example games I used are filed under the Planning section of the Canon.
king hunt sacrifice:
a sacrifice whch exposes the K in a way that it cannot retreat e.g. Qxh6+, Kxh6; Rh3+, Kg5 and the hunt is on!
King hunt:
a chase of the King across the board - which often arises after a sacrifice. [example?] Examples in the Attacking section of the Canon.
King's field combination:
a combination involving the squares directly attacked by the King directly e.g. involving Nxf7. Examples in the Attacking section of the Canon.
Knight defender:
the stalwart N on f3/f6 in front of the castled King.
knight wheel:
a five-move circling motion of the N to attack the square next to it, e.g. Nb1-a3-c4-e3-d1 to attack b2. A game Capablanca-Yates is an [example?].
latitude of the draw:
to retain enough access and control over all disputed areas of the board to avoid the risk of losing, assuming with fair play on both sides. It may be that commitment to an attack in one area risks losing the game because of loss of control elsewhere. This is an underlying theme of the Averbach-Keres game in the Errors section of the Canon.
line piece:
Rook or Bishop
line-clearance sacrifice:
a sacrifice to open up a line e.g. Nf4 when ...exf5 opens up a line for a B on b2 The move 11.d6 model game Morphy-Meek is both a decoy and a line-clearance sacrifice of a Pawn.
liquidating sacrifice:
a sacrifice, perhaps only temporary, to secure exchanges. The 45th game of the first Karpov-Kasparov match in the Defence section of the Canon is a superb example of this.
exchange of several pieces in succession, perhaps involving a forcing or temporary sacrifice. The examples given in the Bishops handout feature the Stahlberg/Capablanca manoeuvre, the aim of which is a defensive liquidation.
little centre:
the squares e4/d4/e5/d5. Also known as the basic centre.
long diagonal:
either of the diagonals a1-h8 or h1-a8. A Bishop developed in fianchetto (q.v.) sits on the long diagonal, and influences the little centre (q.v.).
long side:
for a passed pawn on d6, the long side is the files e-h, important in Rook endings.
lose a tempo:
to use one more move than necessary in development or manoeuvre, thereby disadvantageously falling behind in development or in a Pawn race. See the rules and examples from the Canon. Contrast with losing the move.
lose the exchange:
to lose a rook for a bishop or a knight
lose the move:
to use more moves than necessary in development or manoeuvre, thereby advantageously gaining the opposition or creating Zugzwang. Contrast with losing a tempo.
Lucena position:
- an important winning position in a Rook ending.
main line:
in analysis, particularly of the opening, the principal variation used or analysed. See the Analyis section of the Canon.
major pieces:
the Queen and Rooks
more pawn on one side than the opponent, e.g. four pawns on efgh files against 3 pawns on fgh, with an open d-file
majority attack:
the attack with a majority of pawns, to create a passed pawn or break through to attack. See Marshall-Capablanca and Alekhin-Marshall in the Pawn mobility handout.
Modern Chess Openings
the game after the players have wholly or mostly finished development.
a square which when occupied triggers a combination [example?]
minor exchange:
to lose bishop for knight (not always a disadvantage). See the bishops handout.
minor pieces:
Knights and Bishops
fewer pawns on one side than your opponent, e.g. 2 pawns on a+b-files against three pawns on abc.
minority attack:
to attack on a side where you have fewer pawns, to create a weakness in the majority. A difficult but important theme in the Pawn mobility handout.
freedom to manoeuvre, often because of control of Space, an important Strategical Theme.
mysterious Rook move:
a purposeful move of a Rook to a file which is not at present open (but may become so); one of Nimzovotch's colourful usages. [example?]
N =
Novelty (see TN)
NM =
National Master
when a piece moves in front of an enemy Pawn it obstructs its advance (see blockade) [example?]
occupation of centre:
to move pieces and pawns toward the centre e.g. to play Pc3,d4,e4, Nf3,d2, Bc4,e3. Several examples under "centralisation" in the Strategical Themes section of the Canon.
offside piece:
a piece on the side of the board, possibly distant from the main theatre of combat. A couple of examples in the Strategical Themes section of the Canon.
open game:
a position without locked pawn chains in the centre, often arising from 1. e4 e5; see the Pawn formations handout, and material on example openings.
opening trap:
a trap in the opening. The Traps section of the Canon is full of them.
the first moves of a game where the players are completing their development.
opposite coloured bishops:
having one bishop each which travel on different coloured squares; makes defence harder in the middle game, easier in the endgame. Examples, as always, in the Canon, but there is also a handout on Bishop endings.
opposing Ks on e4 and e6 cannot pass without one giving way - but the one that gives way is the first to move, e.g. 1.Ke4-d4, Kf5; 2.Kd5, Kf4 and Black passes with gain of tempo. This is described briefly in King and Pawn endings. See also conjugate squares.
Over-the-board (as opposed to correspondence/postal chess)
a square which cannot easily be attacked by pawns, suitable for occupation by a knight or other piece. 1. e4 e5 creates potential outposts on d5/f5 for White and d4/f4 for Black. Nc3-d5 may be met with ...c6, but if White plays Nd2-f1-e3-f5 Black may hesitate before playing ...g6 which may create holes in front of the king. See the Knights handout.
outside the square:
when chasing a passed pawn, the K needs to be close enough to catch it - it will be close enough if it is inside a square drawn with the pawn at the corner and the 'home run' to the last rank as the side. So for a Pc5 the square is c5-g5-g8-c8, and if the Black K is outside (and cannot move in on the next move), the Pawn will queen.
a piece or Pawn with too many defensive tasks is overloaded. There are examples in the Tactics section of the Canon.
overloading sacrifice:
a sacrifice to overload a defender e.g.Nxh7 may overload a Nf6 which defends h7 and e8. There are examples in the Tactics section of the Canon.
to over-defend a point e.g. e4 is overprotected with Bc2, Nd2, Re1, Qe2, Ng3. The idea is that after e.g. Nf5 and an exchange ...Bd7xf5, the recapture e4xf5 will suddenly open up lines for the patient White pieces. Nimzovitch seemed to say that overprotection is an end in itself, but more plausible is that over-protection may make a strong move like Nf5 more decisive. There are examples in the strategy/themes section of the Canon.
passed pawn:
a pawn with no opposing pawns in front or to the sides, which can therefore advance without being exchanged by a pawn; often the only way to win once Queens are exchanged. See the Endgame advice.
pawn chain:
connected pawns which protect each other e.g. c3-d4-e5. See the Pawn formations handout.
pawn islands:
Capablanca's term for groups of connected pawns, separated by (half-) open files. White with Pawns on a2, b2, d3, e4, f4 and h3 has three Pawn islands. There is an example in the handout On manoeuvres.
pawn lever:
Kmoch's term for a pawn move that tries to open lines, especially a file. See Pawn Break
pawn majority:
a greater number of Pawns, usually on a wing e.g. White: Pa2, Pb2, Pc2 Black: Pa6, Pb5. See majority attack.
pawn race:
in an endgame where Pawns on each side race to promote - usually in a King and Pawn endgame where the Pawns cannot be captured or obstructed.
pawn sacrifice:
a sacrifice of a pawn, often called a gambit in the opening
penetrating sacrifice:
a sacrifice to get into the heart of the defences e.g. Ng5xf7 against a king castled behind a fianchetto. There are examples in the Attacking section of the Canon.
a triangle of pawns e.g. b3-c4-d5-e4-f3 in the KID and Colle System.
Philidor position:
- usually, the important drawing position in a Rook ending. Also, a winning position in the ending of Rook and Bishop against Rook.
a piece standing between an opponent's line-piece (N/R/Q) and a piece of your own of a higher value is pinned. After 1. e4 d6 2. Nf3 Bg4 the Nf3 is pinned. There's a handout on Pins
positional sacrifice:
a sacrifice played for long-term positional gain e.g. in the Sicilian defence ...Rc8xNc3 to double the White pawns and weaken d5/e4; a nice defensive positional sacrifice was made by Petrosian against Reshevsky, collected in the Defence section of the Canon.
preventive retreat:
a retreat made in anticipation of an attack (rather than reacting to it) [example?]
prevention. Nimzovitch talked about this rather as an end in itself, which is misleading. [example?]
propitiating sacrifice:
a defensive sacrifice, hoping to slow up the attack long enough to organise a defence [example?]
Queen's Gambit Accepted
Queen's Gambit Declined
Queen hunt:
to chase and close down the space available to a Q, with the aim of winning it - see the handout on Kings and Queens, and the Tactics section.
the rows of squares, e.g. a2-h2 is White's second rank, Black's seventh.
to give up a losing game before mate. It is polite to do so, and perhaps less painful for yourself, but some players play on in the hope of their opponent blundering.
restricted centre:
adopting a modest central formation with pawns on e.g. e6/d6. See the Pawn formations handout.
retrograde manoeuvre:
to move backwards - e.g. Nc3-d1 so as to play c3. There is an example of this by Botvinnik in the style section of the Canon.
sacrifice for draw:
a sacrifice which has a draw rather than a win as the aim, e.g. to sacrifice Nxg5 for one of two pawns in the ending, leaving a Bd3 unable to support a Ph4 against a K on g7/h8, or to achieve a perpetual check. See the Defence section of the Canon.
sacrifice for space:
to play e.g. the Cochrane Gambit in the Petroff 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4.Nxf7 which gains time to secure the advance of the central pawns.
to give up material - if you can see how you can win back the material quickly, it is called a combination or sacrificial combination, if you are just hoping to get a lasting initiative and cash in later, it is sometimes called a speculative sacrifice or, following Spielmann, a real sacrifice. Spielmann referred to sacrificial combinations as 'sham' sacrifices. Tartakower and DuMont describe a dozen types of sacrifice, found elsewhere in this Glossary.
short for the seventh rank (a2-h2 or a7-h7) - a good place for a rook.
seventh rank:
the rank a7-h7 (or a2-h2 from Black's side), which may be powerfully occupied by a R in the ending. A famous example Capablanca-Tartakower is given in the appropriate handout.

 Nimzovitch used the term seventh rank absolute for control of the seventh rank by a Rook, with the enemy King trapped on the back rank, as in that game.

short side:
for a passed P on d6, the files a-c are the short side - crucial in Rook endings.
skewer (X-ray attack):
attack by a line piece on an enemy piece behind which is another enemy piece e.g. White Rd1, Black Bd5, Bd7. There are examples in the Tactics section of the Canon.
SM =
Senior Master
smothered mate:
a K mated usually by a N when all the escape squares are occupied by friendly men e.g. Nf7+ with Kh8,Rg8,Pg7/h7. See the handout on Basic Mates.
no mate, but no possible (legal) moves for one side is stalemate - often occurs with a lone K when the attacking side overlooks the idea e.g. Kf6,Qd6 with K on e8 to move is stalemate. See the handout on Basic Mates.
strong points:
squares where you dominate e.g. the square e5 is often a strong point for Black after playing Pe5, Re8, Nbd7 and Pd6 or Bd6. A hole for your opponent may be a strong point for you; this is mostly clearly see with respect to Knight outposts .
(Arabic) Originally one of the conventional starting formations for play, now used to describe key positions arising from the opening. The examples given under transposition in the Canon are good examples.
TD =
Tournament Director
a move lost or gained, often used in discussing the opening. [example?]
tempo - fight for tempo:
for example, after 1. d4 d5 2. c4, if Black plays ...dxc4 White will play e3 and Bf1xc4. If Black waits until White has already played e3 and Bd3, and then plays ...dxc4, White will of course play Bxc4 but will have lost a move (Bf1-d3xc4). So White will try to wait, and Black will also wait - hence the Tempo Struggle Variation 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 Be7 5. e3 O-O 6. Nf3 Nbd7 7. Rc1 Re8 8. Qc2 c6 9. a3 a6 10. h3... where White won't yet play Bd3 and Black won't yet exchange.
temporary sacrifice:
a sacrificial combination where the regain of material can be foreseen [example?]
TN =
Theoretical Novelty: A new idea in an opening line (usually used when a GM first tries it).
a plausible move that loses to a hidden or unexpected combination - e.g. 1. e4 e5 2. f4 Bc5 is a simple trap, since the obvious 3. fxe5 fails to 3...Qh4+. 2...Bc5 is also a well-motivated move in its own right, and is to be preferred to playing poor moves for the sake of setting a trap that the opponent may spot. The Traps section of the Canon is full of both sorts!
a common Zugzwang position, e.g. White Ke5, Pd4; Black Kc4, Pd5.
to move all three major pieces onto a file, as in the Alekhin-Nimzo game in the handout on Pins.
two bishops:
having both bishops where your opponent has only two knights or a bishop and a knight; normally an advantage. See the handout on Bishops.
undermining sacrifice:
a sacrifice to remove a guard e.g. Nxd6 removing the defender of e5, or Ph5-h6 to undermine a Knight on f6 [example?].
to uncover an attack (or defence), e.g. Nf3-e5 may unmask the fianchettoed Bg2. In the Tactics section of the Canon there is an example of each, one under overloading, the other under unmasking defence.
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vacating sacrifice:
to sacrifice a piece thus releasing a square for a more powerful piece e.g. Nh5xg7 allowing Qe2-h5. Pawns are the commonest sacrifice made for this reason. [example?]
to leave a square so that another piece may occupy it, e.g. Rf1-e1 and Bb5-f1 is sometimes played. [example?]
an alternative line of play: see analysis
visualisation (sight of the board):
the ability to picture and assess a position, as might arise in analysis of a possible variation; a common source of error
weak pawn:
a Pawn that cannot easily be defended, e.g. a backward pawn. There are examples in the Strategy/themes section of the Canon.
weak pawns:
generally, a collection of pawns which have some of the features listed above: doubled, isolated, backward... There are examples in the Strategy/themes section of the Canon.
weak square:
a square that cannot easily be defended, and may become a hole or outpost for the opponent. There are examples in the Strategy/themes section of the Canon.
a weak Pawn or weak square There are examples in the Strategy/themes section of the Canon.
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an alternation of checks and captures e.g. White Rg7, Bf6, Black Kh8 - the famous Torre-Lasker game is in the Tactics section of the Canon.
wrong bishop:
a Bishop which does not control the Queening square of a Pawn, e.g. White: Kg3, Bf3, Pg4, Ph4, Black Kg8, Nf6 - the move ...Nxg4 draws for Black despite the loss of the piece. See the Bishop endings handout.
(German) time trouble [example?]
(German) where a side is satisfactorily defended, but any move will upset the defence - and they must move! This is not unusual in Rook endings and other simplified positions - indeed, the opposition and trebuchet are examples of Zugzwang - but it is most unusual with more pieces on the board, although Nimzovitch fanously managed it against Samisch, a game found in the Pawn Mobility handout.
(German) literally, in-between move. When, for example, a re-capture is delayed for a move to make a capture, check or threat elsewhere. [example?]

Dr. Dave the player who put the gloss in glossary.
"Wipe your glosses with what you know." -- Joyce