Definition of rack (noun)

A geometric form, usually aluminum, wooden or plastic, used to assist in setting up balls in games like eight-ball, nine-ball, and snooker. The rack allows for more consistently tight grouping of balls, which is necessary for a successful break shot. In most games a triangle-shaped rack capable of holding fifteen balls can be employed, even if the game calls for racking less than a full ball set, such as in the game of nine-ball. For further information, see the Rack (billiards) main article.
In some games, refers to a single frame.

24 Random Essential Billiards Terms

A tight, Spandex glove covering usually most or all of the thumb, index finger and middle finger, worn on the bridge hand as a more convenient and less messy alternative to using hand talc, and for the same purpose: a smooth-gliding stroke.
A game of pool played on a table shaped like a rectangle, with or without pockets.
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.
Any system for banking or kicking balls multiple rails which uses table diamonds as aiming references.
This is a style of play where the player is required to stay on top of all the scoring practices. Scratches and points will disappear if they are not remembered.
This is a ball that is resting on the edge of a pocket, and would be a very easy shot to pocket.
This is also used to describe the ball when it rests on the edge of the pocket, almost begging to drop.
Principally British: In snooker, if a player wins all of the required frames in a match without conceding a frame to their opponent - for example, if a player wins a best-of-nine-frame match with a score of 5-0 - this is referred to as a "whitewash". This term is based on a similar term used in the card game of "patience" in the UK. However, it is not used in the context of a 1-0 winning scoreline in a match consisting of a single frame.
See overcut.
This is a bank in one pocket pool that is sitting at an angle that makes it unsafe to play.
This is to win a game by pocketing enough balls before you opponent.
A two-piece cue constructed to resemble a house cue, with a near-invisible wood-to-wood joint. The subterfuge often enables a hustler to temporarily fool unsuspecting fish into thinking that he or she is an unskilled banger with no regard for finesse or equipment quality. Many league players also use cheap but solid sneaky petes as their break cues.
This is a timing device for monitoring and restricting shot times for a player.
A shot in which the cue ball is struck above its equator with sufficient top spin to cause the cue ball to travel forward after it contacts an object ball. When a cue ball with follow on it contacts an object ball squarely (a center-to-center hit), the cue ball travels directly forward through the space previously occupied by the object ball (and can sometimes even be used to pocket a second ball). By contrast, on a cut shot, a cue ball with follow on it will first travel on the tangent line after striking the object ball, and then arc forward, widening the carom angle.
This is a term to describe 100 break points in a game of snooker.
This is a table that offers poor conditions for play; it is either dirty, wet, or overall poor quality.
This is when you win a game of one pocket on your opponents break.
A short and loose stroke performed in a manner similar to the way one throws a dart; usually employed for a jump shot. See also nip draw.
Also the hook. In snooker, a type of mechanical bridge that has only recently been endorsed by the WPBSA to allow its use in major tournament play. It is a normal rest with the head in line with the shaft, but the last foot or so of the shaft is curved. This allows players to position the curved end around an obstructing ball that would have otherwise left them hampered on the cue ball and in need of a spider or swan with extensions, which would have less control.
Often times a protective finish is applied to a cue stick after construction. A UV polyurethane is common, and this helps to protect the cue from fading and dings.
Anything that causes a foul according to the rules of a game.
Same as angle of reflection.
Same as gutter table. A table with a ball return system, as opposed to a drop pocket table.
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.
Pocket openings that are significantly wider than are typical and thus allow shots hit with a poor degree of accuracy to be made that would not be pocketed on a table with more exacting pocket dimensions.