Definition of clean

This refers to a shot that is not banked, does not hit a rail and goes into the pocket without contacting any other balls on the table.

24 Random Essential Billiards Terms

When the object ball lies behind another ball which makes it impossible to be struck by the cue with a direct hit.
American Poolplayers Association. This is the largest association of pool players in the world, and includes The Canadian Poolplayers Association. With numerous tournaments, including the U.S. Amateur championship, they are a force on the competition scene.
The APA has established the use of the "Equalizer" which offers handicaps to players and equalizes the playing field like in golf.
Also goose neck rest. Same as swan.
This is the act of keeping your ball location advantages the way they are, and not allowing your opponent to even things out in the game of one pocket.
Named after Chicagoan J. E. Parker, it is a 3½ × 7 inch box drawn on a balkline table from the termination of a balkline with the cushion, thus defining a restricted space in which only a set number of points may be scored before one ball must be driven from the area. Now supplanted by anchor spaces, it was developed to curtail the effectiveness of the anchor nurse, which in turn had been invented to exploit a loophole in balkline rules: so long as both object balls straddled a balkline, there was no restriction on counts, as each ball lay in a separate balk space.
In snooker, the colour ball worth 5 points, whose spot is at the center of the table.
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.
Five-pin billiards is a today usually a carom but sometimes still a pocket form of cue sport, popular especially in Italy and Argentina but also in some other parts of Latin America and Europe, with international, televised professional tournaments. The game is sometimes referred to as Italian five-pins or Italian billiards.
A soft joint-like plastic or linen base material. It lets the cue whip, putting more English on the cue ball.
Used with an amount to signify money added to a tournament prize fund in addition to the amount accumulated from entry fees (e.g. "$500 added").
This is a term used to refer to all the different aspects involved in setting up a shot, i.e. the stance, grip, bridge, and stoke.
This is a tip tool for cleaning the edges of you tip after mushrooming occurs.
See two-shot carry.
This is playing to a higher winning score than eight in the game of one pocket.
To fail to make a legal shot.
Also string off. Chiefly British; Obsolete: Same as string or lag.
A foul where the rules are blatantly, intentionally violated, with a stiffer penalty (e.g., loss of game) than normal.
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 player that will regularly loose money to a particular player that is obviously a better player.
A chiefly British term for a set of mechanical bridges. British-style rests differ from most American-style rake bridges in shape, and take several forms: the cross, the spider and the swan (or goose neck), as well as the rarer and often unsanctioned hook. When used unqualified, the word usually refers to the cross. Rests are used in snooker, English billiards, and blackball.
This playing to a number less than eight in a game of one pocket.
A player who during the course of a tournament does not lose focus. Typically said of those players that regularly make it to the finals of a tournament.
Either to hit the balls hard with no intention in mind other than to get lucky (or 'hit-and-hope'), or to shoot hard at the money ball ball with the same intention. Compare slop and fluke.
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.