Definition of cluster

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

24 Random Essential Billiards Terms

One-on-one game play.
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.
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.
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.
Also pro side of the pocket and missing on the professional (or pro) side of the pocket. Sometimes "of the pocket" is left off the phrase. To err on the side of overcutting a difficult corner pocket cut shot rather than undercutting in nine ball; "missing on the professional side of the pocket." So called because experienced players understand that on a thin cut, overcutting the object ball to a corner pocket will far more often leave the object ball in an unfavorable position for the incoming opponent than will an undercut, which often leaves the object ball sitting in front of or nearby the pocket it had been intended for on a miss. By contrast, in eight-ball, except when both players are shooting at the 8 ball, the incoming player after a miss is shooting for different object balls, so this maxim does not apply, and the opposite may be good strategy as, if the object ball stays near the pocket through an undercut, it is advantageously positioned for a subsequent turn and may block the opponent's use of the pocket.
A unit of scoring, in games such as snooker and straight pool with numerical scoring.
A unit of scoring, in team matches in leagues that use numerical scoring instead of simple game/frame win vs. loss ratios.
Another term for knuckle / tittie.
Using knowledge of the game and one's own abilities and limitations to choose the manner of shooting and the particular shot from an array presented, that has a degree of likelihood of success. This often requires a player to forego a shot that if made would be very advantageous but does not have a high likelihood of success, in favor of a safety or less advantageous shot that is more realistically achievable.
Either of the two shorter rails on a standard pool, billiards or snooker table. Contrast side rail/long rail.
Also known as a Dead cushion. A cushion that has either lost a degree of elastic resiliency or is not firmly bolted to the frame, in both cases causing balls to rebound with less energy than is normal.
This is a carom shot that utilizes english and only two rails to achieve three cushion contacts.
To fail to make a legal shot.
Random method for pairing of opponents when setting up a bracket system for a tournament.
These are fouls made in one turn and then on the next by the same player each time. Some games have a rule that a player will lose the rack or match with three succesive fouls.
Three Ball is a pocket billiards folk game played with three standard pool object balls and a cue ball. The goal is to pocket the three object balls in as few shots as possible.
Be in a game where either because of disparity in skill level, or because of a handicap given, it would be very difficult to lose.
A 7 inch (17.8 cm) square box drawn on a balkline table from the termination of a balkline with the rail, thus defining a restricted space in which only 3 points may be scored before one ball must be driven from the area. It developed to curtail the effectiveness of the chuck nurse, which in turn had been invented to thwart the effectiveness of the Parker's box in stopping long, repetitive runs using the anchor nurse.
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.
Confederation Panamerica of Billiards
This is to use running english or soft speed in order to open up the angle on a particular bank shot.
A combination shot, where hitting the first ball rubs it against the center connecting line of two frozen object balls throwing the second out.
Short for left english (side), i.e. spin imparted to the cue ball by stroking it to the lefthand side of its vertical axis. Contrast right.
This is the way a ball rolls when impeded by something on the table or a blemish in the cloth, often times regular players will remember certain rolls and play to them.
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).
To apply chalk to the tip of your cue before a shot.