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

To fail to make a legal shot.
Describes a cue ball sliding on the cloth without any top spin or back spin on it.
To "give someone weight" is to give them a handicap so the game is more even in skill level. If one player is significantly better than the other in a game, then you can add some weight, more or less balls for someone, to even the difficulty load between each player.
Any system for banking or kicking balls multiple rails which uses table diamonds as aiming references.
A stroke in which the cue's tip glances or slips off the cue ball not effectively transferring the intended force. Usually the result is a bungled shot. Common causes include a lack of chalk on the cue tip, a poorly groomed cue tip and not stroking straight through the cue ball, e.g. because of steering.
The sides of a table's frame upon which the elastic cushions are mounted. May also be used interchangeably with cushion.
One of two sharp, jutting curves of the cushions either side of a pocket at the points where cushion and pocket meet, forming the jaws of the pockets. Also known as a point, a tittie or a horn.
A cluster of balls. In snooker, the bunch of reds that are typically left below the pink spot in the early stages of a frame, not including those reds that have been released into pottable positions.
Same as angle of reflection.
Any shot in which the cue ball or an object ball has to squeeze by (just miss with almost no margin for error) another ball or balls in order to reach its intended target.
Hitting the object ball with too large of a cut angle; hitting the object ball too thin. It is a well-known maxim that overcutting is preferable to undercutting in many situations, as is more often leaves the table in a disadvantageous position on the miss than does an undercut. See also professional side of the pocket.
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.
To give a handicap to an opponent where they have to win a specified number less games than the other player in order to triumph in the match. The name refers to posting games on the scorekeeping mechanism known as a wire, though it is employed when no actual use of the particular device is available or intended.
When you have completed a shot by pocketing a ball into a pocket.
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.
This is a shot on the cue ball that will push through to a frozen ball on the cue ball. If the contact is made on the object ball while the cue stick is still contacting, essentially pushing the second ball, then it is usually considered a foul.
A British term (especially in snooker) for the splitting of a group of balls when another ball is sent into them, typically with the intent of deliberately moving them with the cue ball to develop them.
Short for top spin, i.e. same as follow.
Chiefly British: The half of the table in which the object balls are racked (in games in which racked balls are used). This usage is conceptually opposite that in North America, where this end of the table is called the foot. In snooker, this is where the reds are racked, nearest the black spot; this is the area in which most of the game is usually played.
Chiefly American: Exactly the opposite of the above - the head end of the table. No longer in common usage.
Nickname for the nine ball, usually only used when playing the game 9-Ball.
One of the two pockets one either side of a pool table halfway up the long rails. They are cut shallower than corner pockets because they have a 180 degree aperture, instead of 90 degrees. In the UK the term centre pocket or middle pocket are preferred.
Given to the opposite player after a scratch on the cue ball has been played. This means the player with the cue ball in hand can position it wherever on the table he pleases. Sometimes there are restrictions as to where on the table the ball can be placed: in the kitchen, within the half circle, within the D. This is also known as cue ball in hand.
1.A (usually unmarked) line running across the table between one diamond and its corresponding diamond on the opposite rail. See also head string, foot string, long string for examples.
2.Same as wire, sense 2. Can be used as a verb, as in "string that point for me, will you?"
3.A successive series of wins, e.g. of games or frames in a match or race.
4.Chiefly British; same as lag.
Derived from "sitting duck", usually referring to an object ball sitting close to a pocket or so positioned that is virtually impossible to miss. Same as hanger (US, colloquial), sitter (UK).
This refers to the cluster of balls remaining in a similar position to where they were within the break.