Pool (cue sports)
Pool, also more formally known as pocket billiards (mostly in North America) or pool billiards (mostly in Europe and Australia), is the family of cue sports and games played on a pool table having six receptacles called pockets along the rails, into which balls are deposited as the main goal of play. Popular versions include eight-ball and nine-ball. An obsolete term for pool is six-pocket.
There are hundreds of pool games. Some of the more well known include eight-ball, nine-ball, ten-ball, straight pool, one-pocket and bank pool.
There are also hybrid games combining aspects of both pool and carom billiards, such as American four-ball billiards, cowboy pool and bottle pool.
Etymology
The Oxford English Dictionary states that pool is generally "any of various types of billiards for two or more players" but goes on to note that the first specific meaning of "a game in which each player uses a cue ball of a distinctive colour to pocket the balls of the other player(s) in a certain order, the winner taking all the stakes submitted at the start of the contest" is now obsolete and its other specific definitions are all for games that originate in the United States of America.