1. In snooker, the highest-value colour ball on the table, being worth seven points. It is placed on the black spot. In some (especially American) snooker ball sets it is numbered "7" on its surface.
2. Chefily British: The black ball (usually numbered "8") in standard blackball and traditional 8-ball pool, or the slightly larger but otherwise identical number 8 ball in a Kelly pool set (a.k.a. an "American" or more properly a standard WPA pool set). See also 8 ball.