What is an open file in chess?

A file - one of the eight columns - with no pawns of either colour on it. It matters because a rook on an open file sees all the way down the board, and getting a rook onto one is the most reliable plan there is in a middlegame with no other plan.

What is a passed pawn?

A pawn with no enemy pawn in front of it and none on either adjacent file that could ever capture it. Nothing but pieces can stop it, which is why a passed pawn is worth going out of your way for: in an endgame it is often simply a queen with a delay.

What does tempo mean in chess?

One move, counted as a unit of time. To gain a tempo is to make a move that forces a reply, so you get a free move somewhere else; to lose one is to move the same piece twice for no reason. It is the currency the opening is played in.

A square in or near enemy territory that is defended by one of your pawns and can never be attacked by one of theirs. A knight on an outpost cannot be driven away by a pawn, so it sits there for the rest of the game - which is why they are worth more than knights normally are.

What is luft in chess?

German for "air": a pawn move in front of a castled king that gives it an escape square. It costs a move and it prevents the back-rank mate, which is the most common way a game between reasonable players ends in disaster.

What is a blunder, and what does en prise mean?

A blunder is a move that loses material or the game outright to something the player simply did not see - traditionally written with two question marks. En prise, from the French for "in take", describes a piece that is attacked and undefended: it is not yet a blunder, it is the thing a blunder leaves behind.

Chess Terms

Chess vocabulary is mostly shorthand for a picture. Here are the words that come up in every commentary and every lesson, each one attached to the position it is actually describing.

By Nethanel Bar, Co-founder & CEO

Last updated August 27, 2026

Most chess vocabulary is shorthand for a picture. Nobody says "the column with no pawns of either colour on it" twice; they say open file and move on.

So here are the words, each attached to the position it names.

Words about pawns

A passed pawn has no enemy pawn in front of it and none on either neighbouring file. Nothing except pieces can stop it, which in an endgame usually means nothing can.

Interactive board

White has two pawns, on c5 and f3. Tap the one that is passed.

the word	what it means
passed pawn	no enemy pawn in front, and none on either adjacent file
doubled pawns	two of your own pawns on the same file - they cannot defend each other
isolated pawn	no friendly pawn on either adjacent file; only pieces can ever defend it
backward pawn	behind its neighbours and unable to advance safely, usually on an open file
pawn chain	pawns defending each other diagonally; the one at the bottom is the base and the target
promotion	reaching the last rank and becoming another piece
en passant	the capture of a pawn that has just gone two squares, as if it had gone one

Words about lines and squares

An open file is a file with no pawns on it at all. Half-open means no pawns of your colour, which is nearly as good, because your rook still sees down it.

Interactive board

The c- and d-files have no pawns on them at all. Put your rook on one.

A fianchetto: the bishop developed to g7 behind its own g-pawn, where it looks down the whole long diagonal. Black's king is castled behind it, which is the other half of the idea - and the same structure on the b-file is a queenside fianchetto.

the word	what it means
open file	no pawns of either colour on it; a rook's natural home
half-open file	no pawns of your colour on it - you attack down it, they defend across
outpost	a square you can defend with a pawn and they can never attack with one
fianchetto	a bishop developed to b2, g2, b7 or g7, behind its own pawn
battery	two pieces lined up on the same line - rook behind rook, or queen behind bishop
luft	a pawn move giving your castled king an escape square from the back rank
back rank	your own first rank, where the checkmate happens if you never made luft

Words about time and material

Tempo is one move, counted as time. You gain one when your move forces a reply and lose one when you move a piece twice for nothing. The whole opening is an argument about tempi.

the word	what it means
material	the pieces you have, counted in points: pawn 1, knight and bishop 3, rook 5, queen 9
tempo	a single move, thought of as time; you gain one by forcing a reply
development	getting your pieces off their starting squares and into the game
initiative	being the one making threats, so your opponent's moves are all answers
en prise	attacked and undefended - a piece sitting there to be taken
blunder	a move that hands over material or the game to something you did not see
zwischenzug	an in-between move: instead of recapturing at once, you insert a check or a threat first
prophylaxis	a move that stops the opponent's idea before it starts
zugzwang	every legal move you have makes your position worse - and you must move

Words about attacking

These four are the ones worth learning as pictures rather than definitions, and each has its own page.

the word	what it means
fork	one piece attacking two at once, so only one of them can be saved
pin	a piece stuck in front of a more valuable one and unable to move
skewer	the same line with the valuable piece in front, forced to move and abandon what is behind
discovered attack	moving one piece so that the piece behind it does the attacking

Words about how a game ends

the word	what it means
check	the king is attacked and must be saved this move
checkmate	check with no legal answer - the game ends immediately
stalemate	no legal move and the king is not attacked: a draw
resign	to concede rather than play a hopeless position out
insufficient material	neither side has enough left to force mate, so it is drawn on the spot
fifty-move rule	fifty moves with no capture and no pawn move: either player may claim a draw
threefold repetition	the same position three times: either player may claim a draw

Try it

One of White's two pawns is passed. Tap it.

Common questions

What is an open file in chess?: A file - one of the eight columns - with no pawns of either colour on it. It matters because a rook on an open file sees all the way down the board, and getting a rook onto one is the most reliable plan there is in a middlegame with no other plan.
What is a passed pawn?: A pawn with no enemy pawn in front of it and none on either adjacent file that could ever capture it. Nothing but pieces can stop it, which is why a passed pawn is worth going out of your way for: in an endgame it is often simply a queen with a delay.
What does tempo mean in chess?: One move, counted as a unit of time. To gain a tempo is to make a move that forces a reply, so you get a free move somewhere else; to lose one is to move the same piece twice for no reason. It is the currency the opening is played in.
What is an outpost?: A square in or near enemy territory that is defended by one of your pawns and can never be attacked by one of theirs. A knight on an outpost cannot be driven away by a pawn, so it sits there for the rest of the game - which is why they are worth more than knights normally are.
What is luft in chess?: German for "air": a pawn move in front of a castled king that gives it an escape square. It costs a move and it prevents the back-rank mate, which is the most common way a game between reasonable players ends in disaster.
What is a blunder, and what does en prise mean?: A blunder is a move that loses material or the game outright to something the player simply did not see - traditionally written with two question marks. En prise, from the French for "in take", describes a piece that is attacked and undefended: it is not yet a blunder, it is the thing a blunder leaves behind.