Definition of double century

Also double-century break. In English billiards, a break of 200-299 points (i.e. double a century). Larger multi-centuries are regularly achieved. Rare in amateur play, triple centuries are routine, and quadruples not uncommon at World Professional Billiards Championships; 2007 winner Mike Russell shot four triples in the final round alone, while of sixteen competitors, three shot quadruple centuries (one once, one twice, and Russell three times). Quintuple centuries are rare even at the professional level, with only the 494 shot by nine-time World Champion Russell (who has more such titles than any other player in history as of 2007) coming close in that event. World Champion Geet Sethi holds the world record, at a duodectuple century (and then some) of 1276 consecutive points."

24 Random Essential Billiards Terms

A gentle tap of the cue ball with the intention of getting it as tight as possible behind another ball, in the hope of a snooker. It is most common in the game of snooker, and is illegal in many pool games, in which on every shot a ball must either be pocketed, or some ball must contact a cushion after the cue ball has contacted an object ball.
Chiefly American: The short rail at the foot of the table. Frequently used imprecisely, to mean foot cushion. Compare top rail; contrast head rail.
The effect of shooting regulation-weight object balls with an old-fashioned over-weight bar table cue ball, such that the cue ball moves forward to occupy (sometimes only temporarily), or go beyond, the original position of the object ball, even on a draw or stop shot, because the mass of the cue ball exceeds that of the object ball. Players who understand smash-through well can use it intentionally for position play, such as to nudge other object balls nearby the target ball. Smash-through also makes it dangerous in bar pool (when equipped with such a cue ball) to pocket straight-on ducks with a stop shot instead of by cheating the pocket because of the likelihood of scratching the cue ball.
This is an imaginary line that separates the halves of the table by crossing at the middle of the side of pockets.
A highly abrasive tip tool used to shape an unreasonably flat new cue tip, or misshapen old one, into a more usable, consistently curved profile, most commonly the curvature of a nickel or dime (or equivalently sized non-US/Canadian coin) for larger and smaller pool tips, respectively. Similar to a scuffer, but deeper and rougher.
A shot aimed so that the center of the cue ball is in line with the edge of the object ball, eclipsing half of the ball. "Hit it just a little thinner than half-ball." Assuming a cling does not occur, the shot will impart post-contact momentum on the object ball in a direction 30° (which is arcsin(1 - x), where x is the fraction of object ball eclipsed: ½ in this case) off the direction of the cue-ball's pre-contact momentum. Also notable because the carom angle the cue ball takes is more consistent than at other contact points.
When the object ball lies behind another ball which makes it impossible to be struck by the cue with a direct hit.
This is the act of looking over the stack, pile of balls in the middle of the table, to see if there are any opportunities in the game of one pocket.
Used when describing perfect cue ball position play.
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".
Used by itself often with "low" and "high": "that's a low-percentage shot for me", "I should really take the high-percentage one".
This is the point on the object ball where the cue exactly impacts or the point at which two balls touch when they impact.
When two or more object balls are frozen or nearly frozen, such that cue-ball contact with one object ball, without the necessity of great accuracy, will almost certainly pocket an intended object ball in the cluster. The most common form of dead arrangements are the dead combination or dead combo (a combination shot in which contact with the first object ball will pocket another one), and the dead kiss, in which contact with the first object ball will pocket it off of another one. See also wired.
Netted or cupped pockets that do not return the balls to the foot end of the table by means of a gutter system or sloped surface beneath (they must instead be retrieved manually).
The profile of the shaft of the cue as it as it increases in diameter from the tip to the joint. A "fast" or "slow" taper refers to how quickly the diameter increases. A "pro" taper describes a shaft that tapers rapidly from the joint size to the tip size so as to provide a long, untapered stroking area.
Literally, a pocket, but generally used in the phrases losing hazard - potting (pocketing the cue ball off another ball - and winning hazard - using the cue ball to pot another ball - the two types of legal shots that pocket balls in games in which the term is used at all, which is very few today. The term principally survives in English billiards, in which both types of shots are point-scoring. Formerly, a large number of different games made use of the two types of hazards as point scorers or losers in various different ways (thus their suggestive names). The term ultimately derives from holes or pockets in the table to be avoided, in very early forms of billiards. While the terms are disused in pocket billiards today, their lingering effect is obvious, as the vast bulk of such games focus on making winning hazards and avoiding losing hazards (a notable exception being Russian pyramid in which both are legal shots).
In golf billiards, an area of the table (sometimes marked) that a player will be penalized for entering if their ball does not leave. Derives from the use of the term in the outdoor game of golf.
A players skill level, ball advantage or match advantage when using a handicapping system.
A natural is an easy shot requiring no side spin. A shot is said to be natural if it does not require adjustments, such as a cut angle, side spin, or unusual force. A natural bank shot, for example, is one in which simply shooting straight into the object ball at medium speed and with no spin will send the object ball directly into the target pocket on the other side of the table.
In snooker, the abandonment of a frame upon agreement between the players, so that the balls can be set up again and the frame restarted with no change to the score since the last completed frame. This is the result of situations, such as trading of containing safeties, where there is no foreseeable change to the pattern of shots being played, so the frame could go on indefinitely.
In pool, placing of the object balls back in the rack, after a foul break.
In snooker, where the cue ball is resting in contact with another ball. If this ball is a ball that may legally be hit, then it is allowable to simply hit away from it and it counts as having hit it in the shot. If the ball moves, then a push shot must have occurred, in which case it is a foul.
This is a play where the shot of the cue ball is meant to end up in a certain place to loose your turn, but makes the next attempt difficult for your opponent. The shot is turned over, but will often times lead to a foul, giving you the ball back with a different view or ball in hand. This "safety" play is important if your shot isn't ideal, and you are likely to turn the ball over anyway.
To play even; without a handicap. Also called heads up.
Sandbagging, in any handicapped sport, is the unethical practice of deliberately playing below your ability in order to alter your handicap so it does not reflect your true ability.
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!