Definition of cluster

Two or more object balls that are touching or are close together.

24 Random Essential Billiards Terms

This is to lay down the money on the table in a betting game before play begins to ensure pay up at the end.
The angle at which a ball approaches a rail, as measured from the perpendicular to the rail.
This is a table that offers poor conditions for play; it is either dirty, wet, or overall poor quality.
Feel generally refers to that elusive quality that makes one cue feel special or superior to another. In essence, it is the cumulative effect of all of a cues characteristics, including weight, shaft diameter, balance, grip material, length, etc. It can vary greatly from one player to another. A cue that feels great to one player does not necessarily fell good to another.
Powdered chalk housed in a cube. This chalk is rubbed into the tip of your cue to help with grip between the tip of the cue and the cue ball. This is more important to use if you are using a medium or hard tip, as opposed to a soft tip, which already provides some good grip. As a warning when purchasing a type of chalk, there is much debate over which chalk offers the best friction, so you best do your research!
A stroking technique in which a player releases his gripping hand briefly and re-grasps the cue farther back on the butt just before hitting the cue ball.
Also topspin, top-spin, top. Same as follow. Contrast bottom spin, back spin.
Same as side rail.
Any mechanical aid that serves to extend the length of the player's cue, normally added to the end of the butt either by clipping around the end or screwing into the base. Though extensions are used for pool, it is more common in snooker because of the significantly larger table size.
In a tournament where players get limited time to make their shots (common in televised matches), an extension is extra time granted before making a shot; players have a limited number of extensions in each frame.
More commonly known as "straight pool", it was for many years the most popular game in pool and the game on which all World Championships were based.
14.1 is a call-shot game played with all 15 numbered balls and cue ball. Every ball pocketed counts as one point and a game is played to a agreed up score, generally 50, 100, or 150 points.
Traditional straight pool matches are played to 150 points.14.1 is also called "continuous pool" because, after the opening break, play continues until a player reaches the winning score. When only one numbered ball is left on the table, the remaining 14 are racked (with the apex ball missing), and play continues.
An imaginary line drawn from the desired path an object ball is to be sent (usually the center of a pocket) and the center of the object ball.
In snooker, the colour ball that is worth three points, being the second-least valuable colour behind the yellow. It is one of the baulk colours.
(Chiefly British) Said of an object ball that can easily be reached by the cue ball, or of a pocket that can easily be reached by a selected object ball, usually directly (i.e. without intervening kick, bank, carom, kiss or combination shots).
Named after Chicagoan J. E. Parker, it is a 3½ × 7 inch box drawn on a balkline table from the termination of a balkline with the cushion, thus defining a restricted space in which only a set number of points may be scored before one ball must be driven from the area. Now supplanted by anchor spaces, it was developed to curtail the effectiveness of the anchor nurse, which in turn had been invented to exploit a loophole in balkline rules: so long as both object balls straddled a balkline, there was no restriction on counts, as each ball lay in a separate balk space.
In pool, the degree to which racked balls move apart upon impact by the cue ball as a result of a break shot.
In snooker, a shot sending the cue ball into the pack of red balls and separating them (after potting the ball-on). At least one split is usually necessary in each frame, since the original triangle of reds does not allow any balls to be potted reliably.
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.
Skilled playing in which knowledge of ball speed, angles, post-impact trajectory, and other factors are used to gain position (i.e. a good leave) after the target ball is struck. The goals of position play are generally to ensure that the next shot is easy or at least makeable, and/or to play a safety in the advent of a miss (intentional or otherwise).
Asian Pocket Billiard Union. The APBU is a member of the WPA.
In snooker, a pot into any of the corner pockets where the cue ball had started in the opposite lengthwise half of the table. In other words, a pot in which the cue ball or object ball crosses an imaginary line joining the middle pockets.
This is when you win a game of one pocket on your opponents break.
Basic cue tip contact points on the cue ball to impart various forms of spin. Top spin is also known as follow, side spin as english, and bottom spin as back spin, draw or screw.Rotational motion applied to a ball, especially to the cue ball by the tip of the cue, although if the cue ball is itself rotating it will impart (opposite) spin (in a lesser amount) to a contacted object ball. Types of spin include top spin, bottom or back spin (also known as draw or screw), and left and right side spin, all with widely differing and vital effects. Collectively they are often referred to in American English as "english". See also massé.
A defensive action taken when a player either has no "makeable" or "high percentage" shot or chooses to leave his opponent in a difficult situation. It is a legal shot and is not considered to be dirty pool. A safety must still conform with the rule concerning hitting the correct ball first and striking a rail afterwards. If a correct ball is accidentally pocketed while playing safe, the shooter must continue to shoot.
This describes a shot where you bank the object ball off of a rail and then sink it in a corner pocket.
Also known as slop. To pocket a ball by luck; "he ratted in the 9 ball"; usually employed disapprovingly.