Definition of diamond

Three equally spaced diamonds are normally between each pocket on a pool table. On a carom table, the pockets themselves are replaced by additional diamonds. Diamonds get their name from the shape of the markings traditionally used; though many today are round, square, etc., these rail markings are still referred to as "diamonds".

24 Random Essential Billiards Terms

In eight-ball and related games, describes the situation in which neither player has yet claimed a suit (group) of balls. Often shortened to simply open: "Is it still an open table?" "Yes, it's open."
The pocket chosen to house the selected ball in your called shot.
An illegal shot (foul) in which the cue stick's tip contacts the cue ball twice during a single stroke. Double hits often occur when a player shoots the cue ball when it is very close to an object ball or cushion, because it is difficult to move the cue stick away quickly enough after the cue ball rebounds from the cushion or object ball.
A shooter's body position and posture during a shot.
White talcum powder placed on a player's bridge hand to reduce moisture so that a cue's shaft can slide more easily. It is not provided in many establishments as many recreational players will use far more than is necessary and transfer it all over the table's surface. Venues that do provide it usually do so in the form of compress cones about 6-inches tall. Some serious players bring their own, in a bottle or a porous bag that can be patted on the bridge hand. Many players prefer a pool glove. Talc is frequently mistakenly referred to as "hand chalk", despite not being made of chalk.
Same as back spin.
This is the apex ball in the triangle, racked on the foot spot in a normal game.
Same as foot spot. Chiefly British today, but also an American usage ca. World War I.
A successful attempt to get out of a snooker.
Same as mechanical bridge; so-called because of its typical shape.
This describes a shot in carom games where the cue ball is driven all the way across the long rail, crossing the table, to score a point.
This is a shot involving contact between the cue ball and an object ball which allows the cue ball to contact another object in order to sink a pocket with the second object ball.
Same as solids, in New Zealand. Compare little, small, reds, low, spots, dots; contrast overs.
A tournament format in which a player is out of the tournament after a single match loss.
Same as side rail.
A common way to keep track of games won when playing for small money is to use a coin that is placed under the rail next to the diamonds on the rail. The center diamond at the head of the table is taken as zero, and each diamond from that is considered to be one game. To go 'around the world' is to beat your opponent so badly that the coin travels all the way around the diamonds on the table.
This is when it is necessary to change a set handicap after play indicates it favors one player more than the other.
Same as break.
This is a term used more in snooker to refer to a follow shot, when the cue ball is hit above center to allow it to follow the object ball after impact.
Anything that causes a foul according to the rules of a game.
To elevate the back of the cue on a shot.
Also littles, little ones, little balls. In eight-ball, to be shooting the solid suit (group) of balls (1 through 7); "you're little, remember", "you're the little balls" or "I've got the littles". Compare small, solids, reds, low, spots, dots, unders; contrast big.
This is a tip tool for cleaning the edges of you tip after mushrooming occurs.
A predetermined number of games, usually played for a specified sum of money. Contrast race (a predetermined number of wins). Informally, sets may refer to gambling more generally, as in "I've been playing sets all day", even when the format is actually races or single games.