Definition of illegal

Anything that causes a foul according to the rules of a game.

24 Random Essential Billiards Terms

Describing a difficult pot: "the awkward cueing makes this shot missable."
This piece of armament keeps the butt of your cue safe from coincidental contact with the floor or other damaging incidents. It is usually made of a rubber composite or other durable or flexible material to absorb impact in the case of a collision.
When a ball is in firm contact with a cushion or another ball.
A shot in which the cue ball is potted after caroming off another ball. In snooker and most pool games doing this would be a fault (foul), but the move will score points in many games in which hazards (as such) apply, such as English billiards, or in the final or game point in Cowboy pool. The term derives from this hazard costing the player points in early forms of billiards.
A rack in the form of an equilateral triangle. There are different sizes of triangles for racking different games (which use different ball sizes and numbers of balls), including the fifteen ball racks for snooker and various pool games such as eight-ball and blackball. A larger triangle is used for the twenty-one ball rack for baseball pocket billiards). The smallest triangle rack is employed in three-ball (see illustration at that article) but is not strictly necessary, as the front of a larger rack can be used, or the balls can be arranged by hand.
The object balls in triangular formation, before the break shot, after being racked. See also pyramid.
Also slop shot. A luck shot. Compare fish, fluke and Lorengo; contrast mark and call. Also sloppy. Descriptive of any game where the rules have been varied to allow luck shots not normally allowed or where no foul rules apply.
Cut Throat is a game of pocket billiards created to support three or five players. Balls are assigned to each player, and the purpose is to sink all the opponent's balls first to eliminate the other players.
More commonly known as "straight pool", it was for many years the most popular game in pool and the game on which all World Championships were based.
14.1 is a call-shot game played with all 15 numbered balls and cue ball. Every ball pocketed counts as one point and a game is played to a agreed up score, generally 50, 100, or 150 points.
Traditional straight pool matches are played to 150 points.14.1 is also called "continuous pool" because, after the opening break, play continues until a player reaches the winning score. When only one numbered ball is left on the table, the remaining 14 are racked (with the apex ball missing), and play continues.
This refers to the distance of deflection that the ball comes off of the cue stick after a hit is applied with side spin on it.
Adjectival expression for a player's deadly game; "watch out, he plays jam up.
To play a shot with the stroke and speed that makes it easiest to pocket the object ball, even at the expense of sacrificing position.
Chiefly British: Short for side spin. In Canadian usage, the term is sometimes used as a verb, "to side".
This is the imaginary line that a ball would need to follow in order for it to result in an effective bank shot.
A shot played slowly and with heavy draw and follow-through so that the cue ball can be struck firmly but with a lot of the pace taken out, allowing more control than just a gentle tap that would travel as far. Also called "Drag Draw".
A geometric form, usually aluminum, wooden or plastic, used to assist in setting up balls in games like eight-ball, nine-ball, and snooker. The rack allows for more consistently tight grouping of balls, which is necessary for a successful break shot. In most games a triangle-shaped rack capable of holding fifteen balls can be employed, even if the game calls for racking less than a full ball set, such as in the game of nine-ball. For further information, see the Rack (billiards) main article.
In some games, refers to a single frame.
A joint type which makes it possible to screw and unscrew the butt and shaft very quickly; faster than standard threads.
This is a unique game played on a table with smaller pockets. The balls are racked in a typical pyramid, but after the break any ball can be the cue ball, and you can score by hitting a ball in or by putting the ball in after bouncing it from another object ball.
Side spin on the cue ball that causes it to roll off a cushion (contacted at an angle) with rather than against the ball's natural momentum and direction of travel. If angling into a rail that is on the right, then running english would be left english, and vice versa. The angle of deflection will be wider than if no english were applied to the cue ball. But more importantly, because the ball is rolling instead of sliding against the rail, the angle will be more consistent. For this reason, running English is routinely used. Also called running side in British terminology. Contrast reverse english.
The Higher Education Snooker and Pool Council is a voluntary, not-for-profit organisation established to promote cue sports in institutions of higher education on the island of Ireland.
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.
In snooker, after particular fouls are committed, the referee can call a "free ball." This allows the next player to assign any ball as "ball on" if he or she is shooting next.
This refers to how a player is playing on a particular occasion (a player's skill level). If their game is good, then they are at a high speed, but if they are not playing up to their potential, then they are playing at a lower speed.
The situation arising in many pool games where a ball is spotted to the table's foot spot or some other specific location and the cue ball must be shot from the kitchen or the "D". There are diamond system aiming techniques for pocketing such shots without scratching the cue ball into a pocket.
This is a particular ball which lends itself to be used as a "blocker" or a "protector."
To use a particular ball as security by playing a safety or leaving it where it will act as one.