Definition of Straight eight

A 7 inch (17.8 cm) square box drawn on a balkline table from the termination of a balkline with the rail, thus defining a restricted space in which only 3 points may be scored before one ball must be driven from the area. It developed to curtail the effectiveness of the chuck nurse, which in turn had been invented to thwart the effectiveness of the Parker's box in stopping long, repetitive runs using the anchor nurse.

Also nurse shot, nursery shot. In carom games such as straight rail, balkline and cushion caroms, where all the balls are kept near each other and a cushion, and with very soft shots, can be "nursed" down a rail on multiple successful shots that effectively replicate the same ball setup so that the nurse shot can be repeated again (and again, etc.). Excessive use of nurse shots by players skilled enough to set them up and pull them off repeatedly at will is what led to the development of the balkline carom billiards game variations, and repetitive shot limitation rules in English billiards. A clear example of why: In 1907, Tom Reece scored a record break of 499,135 consecutive points over a period of five weeks, without a miss, using the cradle cannon nurse shot.

An unintentional and often barely perceptible curve imparted to the path of the cue ball from the use of english without a level cue. Not to be confused with a swerve shot.

When the tip of the cue begins to hang over the sides of the ferrule from constant use. This is the action of mushrooming, and it is important to use a tip tool to reshape the tip to fit the ferrule.

Any shot where the cue ball is intentionally jumped into the air to clear an obstacle

When the object balls in straight rail pool are lined up close to each other, but extending out from the cushion, and you choose to bounce off the first object ball at the cushion and then come back to graze the second object ball. This technique can be used to continue scoring points as long as you are efficient with the shot.

The forward rotation of the cue ball that results from a follow shot. Also known as top spin or top, follow is applied to the cue ball by hitting it above its equator, causing it to spin more rapidly in the direction of travel than it would simply by rolling on the cloth from a center-ball hit. Follow speeds the cue ball up, and widens both the carom angle after contact with an object ball, and angle of reflection off a cushion.

Also on the lemon. Disguising the level of one's ability to play.

The 5 out (meaning the player getting the handicap can win by making the 5, 6, 7, 8 or 9 balls).

The surface of the table used for play (often made with slate).

The ease with which a player is generating cue power, due to well-timed acceleration of the cue at the appropriate point in a shot.

This describes a shot where you bank the object ball off of a rail and then sink it in a side pocket.

Same as cheating the pocket. Principally used in snooker.

This is a simple method of gambling where bets are determined between each game instead of playing matches.

This is to win a game by pocketing enough balls before you opponent.

The ball required to guarantee victory in a match. Sometimes used figuratively to mean the last difficult ball required (chiefly British and usually used in multi-frame matches, particularly snooker).

This is a shot where the cue ball caroms off a number of balls in a pin ball, back and forth, fashion to achieve a shot.

Same as triple.

Also known as a "Dirty Defense" or "Dirty Foul". 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.

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.

To allow an opponent to stop playing a set for money in exchange for something. If a player is winning a set by a wide margin, with $100 on the line, the player could say, "I'll let you out now for $75." This is usually meant to save pride.

Failure to hit an object ball at all with the cue ball. In most sets of rules, this is a foul like any other. However, in some variants of bar pool a table scratch while shooting for the 8 ball is a loss of game where other more minor fouls might not be, as is scratching on the 8 ball (neither result in a loss of game in most professional rules).
By way of drift from the above definition, the term is also applied by many league players to the foul in more standardized rules of failing to drive a (any) ball to a cushion, or to pocket a legal object ball, after the cue ball's initial contact with an object ball.
By way of entirely different derivation ("scratch off the table"), it can also mean knocking the cue ball (or more loosely, any ball) completely off the table.

Also pro side of the pocket and missing on the professional (or pro) side of the pocket. Sometimes "of the pocket" is left off the phrase. To err on the side of overcutting a difficult corner pocket cut shot rather than undercutting in nine ball; "missing on the professional side of the pocket." So called because experienced players understand that on a thin cut, overcutting the object ball to a corner pocket will far more often leave the object ball in an unfavorable position for the incoming opponent than will an undercut, which often leaves the object ball sitting in front of or nearby the pocket it had been intended for on a miss. By contrast, in eight-ball, except when both players are shooting at the 8 ball, the incoming player after a miss is shooting for different object balls, so this maxim does not apply, and the opposite may be good strategy as, if the object ball stays near the pocket through an undercut, it is advantageously positioned for a subsequent turn and may block the opponent's use of the pocket.

The placement of the balls, especially the cue ball, relative to the next planned shot. Also known as shape.