The term "8 ball" can refer to a couple of different things. In the context of billiards or pool, the 8 ball is a black ball marked with the number 8, and it is a key ball in the game of eight-ball. The objective of the game is to pocket all of your group's balls (either solid or striped) and then pocket the 8 ball to win. Informally, "the 8 ball" can also refer to being in a difficult or disadvantaged position, often expressed in phrases like "behind the 8 ball."
The term "8 ball" originates from the game of billiards, where the number 8 ball, uniquely colored black with a white circle and the number 8, plays a pivotal role in the game's rules and objectives. The phrase "behind the 8 ball" is believed to come from the situation in the game where a player is left with no good shots after the 8 ball has been struck, leading to a position of disadvantage.