Definition of extension

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.

24 Random Essential Billiards Terms

(Computerized Numerical Control) This is a special appliance used by many cue manufacturers to design the inlays on a cue to precision accuracy. Often times it is looked down upon because this technology departs from the previous standard of "handcrafting" inlays, using a pantograph tool. However, the new technology allows for much more precise cuts at a quicker pace. If you are looking to save some money and appreciate the man made designs that are computer inlayed in your cue, then CNC is the technology for you.
0-2 Barbecue is a slang billiard term that refers to a single player loosing the first 2 matches in a double elimination tournament. This double loss results in that player being knocked out of the tournament without winning even one game.
In snooker, the cushion opposite the top cushion and bounded by the yellow and green pockets (i.e. same as bottom cushion).
Same as spot
Also known as back spin, a type of spin applied to the cue ball by hitting it below its equator, causing it to spin backwards even as it slides forward on the cloth. Back spin slows the cue ball down, reduces its travel, and narrows both the carom angle after contact with an object ball, and angle of reflection off a cushion. There are several variant terms for this, including "bottom" and "bottom spin" in the US and "screw" in the UK. Draw is thought to be the first spin technique understood by billiards players prior to the introduction of leather tips, and was in use by the 1790s.
Also last pocket. A common rule in informal bar pool, especially bar/pub eight-ball, in which the money ball must be pocketed (potted) in the same pocket as the shooter's last object ball (each player may be said to eventually "own" a pocket, for the duration of the game, in which their 8 ball shot must be played if they have already run out their suit). The variant is not extremely common in the United States or the UK, but is near-universal in much of Latin America (where two cue ball scratches are permitted when attempting the 8 ball shot and count as simple fouls, with only a third scratch constituting a loss of game). Last pocket is also common in North Africa. Last-pocket rules require careful position play, and frequently result in bank and kick shots at the 8 ball.
When playing 9 Ball, a dead ball is an object ball the falls into a pocket when a foul has been committed (for example, the shooter scratches or does not hit the lowest ball first). If keeping score by counting balls fallen, neither player gets the point for that ball.
A shot, especially common in straight pool and in some variants of blackball (but not WEPF/EPA rules), in which a player intentionally commits a foul with the object in mind of either leaving the opponent with little chance of running out or simply to avoid shooting where no good shot is presented and to do anything else would give the opponent an advantage. It is often referred to in straight pool as a "back scratch."
This is an object ball that essentially covers up a path necessary for sinking the desired object ball.
This is English that turns into reverse English after contact with the object ball. This will close up the angle on a bank.
The Equalizer Handicap System is the handicap system developed by the American Poolplayers Association. It makes it feasible for a beginner to have a nearly equal chance in a match against a more highly skilled player.
Australian: Defeated with all seven of one's object balls (in blackball or eight-ball) remaining on the table.
Also known as joint caps. Plugs that screw into/onto the threads of a joint when a two-piece cue is broken down to keep foreign objects and moisture from contacting the joint mechanism.
As an adjective or compound noun: push-out. A rule in many games (most notably nine-ball, after and only after the break shot), allowing a player to "push out" the cue ball to a new position without having to contact any ball, much less pocket one or drive it to a cushion, but not counting any pocketed ball as valid (other foul rules apply, such as double hits, scratching the cue ball, etc.), with the caveat that the opponent may shoot from the new cue ball position or give the shot back to the pusher who must shoot from the new position. In nine-ball particularly, and derived games such as seven-ball and ten-ball, pocketing the money ball on a push-out results in that ball being respotted (which can be used to strategic advantage in certain circumstances, such as when the break leaves no shot on the ball-on, and failure to hit it would give the incoming player an instant-win combination shot on the money ball).
Deviation of a ball from its initial direction of travel. Often the result of a poor-quality table and may be an artifact of the cloth, the bed, a ball with uneven weight distribution, or simply the floor the table stands on being uneven.
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!
When a player is playing flawlessly, just "cannot miss" and the game seems effortless.
Also lows, low, low ones. In eight-ball, to be shooting the solid suit (group) of balls (1 through 7); "you're low, remember", "you're low balls" or "I've got the lows." Compare solids, reds, little, spots, dots, unders; contrast high.
Jargon for a tournament chart, showing which players are playing against whom and what the results are. Often shortened to card.
The forward rotation of the cue ball that results from a follow shot. Also known as top spin or top, follow is applied to the cue ball by hitting it above its equator, causing it to spin more rapidly in the direction of travel than it would simply by rolling on the cloth from a center-ball hit. Follow speeds the cue ball up, and widens both the carom angle after contact with an object ball, and angle of reflection off a cushion.
This is a shot where the cue ball caroms off a number of balls in a pin ball, back and forth, fashion to achieve a shot.

1- Short for "pool shark", poolshark (US); sharp, "pool sharp" (British)

2- Verb: To perform some act or make some utterance with the intent to distract, irritate or intimidate the opponent so that they do not perform well, miss a shot, etc. Most league and tournament rules forbid blatant sharking, as a form of unsportsmanlike conduct, but it is very common in bar pool.
Noun: Another term for hustler.
Noun: A very good player. This usage is common among non-players who often intend it as a compliment and are not aware of its derogatory senses .

Chiefly British: Short for side spin. In Canadian usage, the term is sometimes used as a verb, "to side".
The person who is a provider of all or part of a player's stake (money) for a gambling session in which one is not a player.