What is "nine-ball"

n. A form of pool in which players must hit with the cue ball the object ball with the lowest numerical value, but may legally pot any ball apart from the white; whichever player pots the nine ball wins the game.

Nine-ball (sometimes written 9-ball) is a contemporary form of pool (pocket billiards), with historical beginnings rooted in the United States and traceable to the 1920s. The game may be played in social and recreational settings by any number of players (generally one-on-one) and subject to whatever rules are agreed upon beforehand, or in league and tournament settings in which the number of players and the rules are set by the sponsors. During much of its history, nine-ball has been known as a " money game" in both professional and recreational settings, but has since become established as a legitimate alternative to eight ball, straight pool and other major competition games.

In recent decades, nine-ball has become the dominant tournament game in professional pool, in the World Pool-Billiard Association, Women's Professional Billiard Association and United States Professional Poolplayers Association. Matches proceed quickly, suitable for the time constraints of television coverage, and the fast-paced games tend to keep the audience engaged.

Nine-ball (or nine-ball, 9 ball, 9-ball and other variant spellings) is a pool (pocket billiards) game, played with nine object balls, of which the 9 ball is the game-winning ball. It may also refer to:

• 9 ball, the pool (pocket billiards) ball numbered "9", and colored with a yellow stripe
• 9-ball, a nine-dimensional -ball in mathematics