Quarter Ball
A contact where the line of aim through the centre of the cue-ball passes the outside edge of the object-ball by one-quarter of its width.
See:-  Ball Contacts

Referee
The official in complete control of the game or match. He is responsible for seeing that the rules of the particular game being played are strictly enforced.
See:-  Marker

Rests
Rests were originally developed from the mace and have been made in a variety of lengths and designs to help the player reach shots that he would otherwise be unable
to play.
See:-  Half-Butt · Jigger · Long-Butt · Mace · Spider

Right-Hand Spot of the 'D'
The spot on the right-hand edge of the 'D'.

Uses:-

English Billiards - Snooker -

For spotting the non-striker's cue-ball if the centre spot  of the 'D' is occupied, and only after the striker has made  fifteen consecutive hazards - and only when it is off the  table as a direct result of the non-striker's last stroke.  For spotting the Yellow ball.

See:-  Left-Hand Spot of the 'D' · Spots

Run-Through
Refers to strokes in which the cue-ball travels in more or less the same direction as the object-ball.
See:-  Follow · Follow-Through · Stun Run-Through · Top

Running Side
Left or right-hand spin applied to the cue-ball to increase the angle of reflection and the speed it travels after contact with a cushion.
See:-  Angle of Reflection · Check Side · Side

Safe
A position from which it is very difficult, or impossible, to score.
See:-  Safety Strokes · Shot to Nothing · Snooker/ed

Safety Strokes
The defensive part of games where the striker attempts to leave the balls in a position from which the opponent will find it very difficult to score or play a safety stroke. The intention being to force a mistake from the opponent that leaves an easy shot.
See:-  Safe · Shot to Nothing · Snooker/ed

Screw
Extreme back-spin applied to the cue-ball that makes it revolve in the opposite direction to that in which it is travelling. On a straight shot screw will cause the cue-ball to return along its original path.   (Further information can be found here)
See:-  Back-Spin · Bottom

Set
In the last thirty years or so the distinction between 'Plants' and 'Sets' seems to have been forgotten, and both are now generally known as 'Plants'. But they are different. In a 'plant' the ball struck by the cue-ball enters a pocket, and in a 'set', a ball that touches one struck by the cue-ball is pocketed.
For a 'set' to be 'on' an imaginary line drawn through the centres of the touching balls needs to form a direct line to the pocket, but if this line is just slightly off it can still be made. At the top of the diagram an example shows the first red being struck on the right to send the second red to the left and into the pocket.
See:-  Plant

Shaft
The thinner end of the cue which is normally made of ash or maple. On two-piece cues the shaft ends at the joint.
See:-  Butt · Cue · Half-Butt · Long-Butt · Tip

Short-Jenny - English Billiards
Any in-off similar to that shown in the diagram. In the example given the shot would be played with strong left-hand (check) side to spin the cue-ball into the pocket.
When played correctly the red should be left in the middle of the table.
See:-  Long Jenny · Losing Hazard
            Pocket Side

Shot to Nothing - Snooker
A stroke in which the player attempts to pot an object-ball and leave the cue-ball in the baulk area of the table. If he misses the pot no easy scoring shot will be left, but if he does pot the red the cue-ball may finish favourably for one of the three baulk colours.
See:-  Safe · Safety Strokes
            Snooker/ed

Side
Side-spin is applied to the cue-ball by striking left or right of centre. It has little effect until the cue-ball strikes a cushion at an angle, when the cue-ball will either speed up (Running Side), or slow down (Check Side) as it leaves the cushion.
See:-  Check Side · Pocket Side · Running Side

Slate
The beds of full-sized tables are made from five pieces of perfectly matched slate with each piece weighing nearly four hundred pounds.
In the past, various materials have been used or experimented with, including: cement, iron, marble and wood.
See:-  Bed

Snooker / Snookered - Snooker
Describes the position of the balls when the ball 'on' cannot be hit directly due to an intervening ball; or, after a foul stroke, when a portion of the ball 'on' is covered by a ball 'not-on'.
See:-  Cover

Snooker
Now the most popular billiards game in the U.K., and well over 100 years old. The basic structure of the game has remained unchanged although many rules have been added since the first official ones were published in 1901. In its earliest days the game was called 'Snooker Pool' or 'Snooker's Pool', and while fifteen reds have always been used, the colours were sometimes placed or valued differently than they are today. The rules in J.P. Buchanan's "Pyramids and Pool Games" (pub. 1896) show only five colours being used and they were placed as shown, but each had the same value as they do today.
The current rules are published on the website of the World Snooker Association.
See:-  English Billiards · Snooker Plus · Volunteer Snooker

Snooker Plus
Snooker Plus was invented by Joe Davis who added a purple (10 points) and orange (8 points) to the normal set. He thought snooker was dying and hoped this new variation that allowed greater chances for break-building and a higher maximum of 210 would help to revive the game. At the end of the frame the six normal colours would be taken in their usual order, and then be followed by orange and purple. If the frame was tied, the purple was respotted on the black spot. He introduced it to the public on October 26th 1959 during the News of the World Tournament.
See:-  Snooker · Volunteer Snooker

Spider
A high rest that allows a player to cue over an intervening ball. It takes its name from the long 'legs' that give it extra height.
See:-  Half-Butt · Jigger · Long-Butt

Spots
Used for marking the table to show the exact position where certain balls must be placed according to the rules of the particular game being played. The spots are self-adhesive and usually made from paper, fabric or silk. In professional tournaments these spots are marked with a lead pencil or chalk to allow truer running of the balls.

Spot White - English Billiards
Refers to the cue-ball marked with one or two black spots to differentiate it from the plain cue-ball. This has been the case for centuries, but in recent times the 'spot' white has been replaced by a yellow ball for the benefit of the spectators.
See:-  Cue-Ball · Object-White · Plain Ball · Striker's Ball

Spot Stroke - English Billiards
A favourite of the old-time professionals who used it to make very large breaks until it was banned in 1898. It consisted of repeatedly potting the red ball off its spot, and W. J. Peall was a master of it. He made 3,174 points by the stroke in a break of 3,304 in 1890, and 634 consecutive pots in a break of 1,922 in 1885. Under the current rules the red can only be potted off its spot twice. It is then respotted on the centre spot (or if occupied the Pyramid Spot); and if potted again it is then replaced on its own spot. The maximimum number of consecutive pots now allowed is 15.
See:-  Hazards · Winning Hazard

Stance
Refers to the the way the player stands when at the table and ready to play.

Strength
The amount of force used to play a shot. The stroke is said to be hard or soft according to the strength it is played.

Striker's Ball - English Billiards
Sometimes used to differentiate between the two cue-balls used in the game.
See:-  Cue-Ball · Plain Ball · Spot White

String / Stringing - English Billiards
The method used to determine the order of play in English Billiards. Stringing, is to play from the baulk-line to the top cushion and back to leave the cue-ball as close as possible to the baulk cushion. Before a serious match the players string simultaneously and the winner has the choice of balls and the option of playing the first stroke.
See:-  Choice of Balls · Cue-Ball · Plain Ball · Spot White

Stun
A sharp, powerful stroke played to strike the centre of the cue-ball. On a straight shot the cue-ball will stop dead on contact with an object-ball, or be forced away at a near right-angle on an angled shot.   (Further information can be found here)
See:-  Stun Run-Through

Stun Run-Through
An ordinary Stun but with the cue-ball struck slightly higher. The tiny amount of top-spin that is applied then allows the cue-ball to "run-through" an inch or two after contacting the object-ball.   (Further information can be found here)
See:-  Stun

Swerve
A curved line of travel given to the cue-ball by striking down to the left or right of centre. See:-  Massé

Swing
On any angled shot, this describes the curved path taken by the cue-ball as it is "thrown" away after striking the object-ball. The effect is widely known by those who play billiards but less understood by snooker players. The diagram shows one of the basic billiard shots, and a snooker player, seeing the object-white directly between the red and the pocket, would be less likely to realise that the in-off was not only possible but quite easily made. The shot requires no side-spin and should be played hard enough to bring the red back into the baulk half of the table. The deviation shown in the diagram is exaggerated, so if your unfamiliar with the shot it's worth setting it up to experiment with. You should aim for a half-ball contact and play it either as a plain ball or with a hint of top.
See:-  Force an Angle · Forcing Strokes