Definition of scratch

1- Pocketing of the cue ball in pocket billiards. In most games, a scratch is a type of foul. "Scratch" is sometimes used to refer to all types of fouls.

2- British term/slang for Draw

24 Random Essential Billiards Terms

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).
The overall competition between two players, two pairs of players or two teams of players, usually consisting of a predetermined number of frames or games (sometimes organized into rounds).
The horizontal plane directly in the center of the cue ball, which when hit exactly by the cue tip should impart no follow or draw.
This technique works to keep your shot aligned by eyeing your shot above the table, and then locking your chin into position as you lower down to take your shot.
Random method for pairing of opponents when setting up a bracket system for a tournament.
A line, sometimes imaginary (especially in American pool), sometimes drawn on the cloth, that runs horizontally across the table from the second diamond (from the head rail) on one long rail to the corresponding second diamond on the other long rail. In most pool games, the opening break shot must be performed with the center (base) of the cue ball behind the head string (i.e. between the head string and head rail). The head string intersects the long string at the head spot, and delimits the kitchen (and, in European nine-ball, the outer boundary of the break box). The head string's position is always determined by the diamonds, in contrast to the similar but different baulk line, the position of which is determined by measurement from the bottom cushion (head cushion).
To intentionally miss a shot (that results in a foul) in order to create a position for the cue ball that makes it hard for the other player to execute their shot. Not to be confused with a "Safety", since a safety is a legal hit.
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.
The normal phenomenon where the object ball is pushed in a direction very slightly off the pure contact angle between the two balls. Caused by the friction imparted by the first ball sliding past or rotating against the other ball.
Nearly table-length distance between the cue ball and target object ball, or near cue and object balls and target pocket, i.e. a potentially difficult shot ("you sure left me a lot of green on that one").
The cloth covering the table.
A ball hanging over the edge of 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.

1- A tip tool with fine, sharp points used to roughen the cue tip to better hold chalk after it has become hardened and smooth from repeated impacts with the cue ball. Tappers are firmly tapped on or pressed against the tip. Scuffers serve the same purpose, but are used differently.

2- Describes a shot where one has a chance to miscue. Usually heard in reference to long draw shots. As in, "It's a tip-tapper!".

A tournament format in which a player is out of the tournament after a single match loss.
This is the white ball in carom games which is separated from the clear ball by a marking (usually a dot or spot).
Same as centre pocket.
Sometimes interchangeable with scratch, though the latter is often used only to refer to the foul of pocketing the cue ball. A violation of a particular game's rules for which a set penalty is imposed.
The World Professional Billiards and Snooker Association, founded in 1968 and based in Bristol, England, United Kingdom is the governing body of professional snooker and English billiards. It sets the sports' rules, organises tournaments and the pro-am and pro tours, and engages in various promotional activities.
In snooker, the cushion opposite the top cushion and bounded by the yellow and green pockets (i.e. same as bottom cushion).
This is an object ball that essentially covers up a path necessary for sinking the desired object ball.
The placement of the balls, especially the cue ball, relative to the next planned shot. Also known as shape.
A player who was playing very well but suddenly starts playing badly. e.g. "He was making everything on every shot, then lost his stroke and couldn't hit anything, costing him the match."
Same as duck. Derives from an easily shot ball "hanging" in the pocket.
The pocket in snooker that is closest to the green spot.