Blackball (sometimes written black ball or black-ball) is a pool (pocket billiards) game. It is called blackball as opposed to 8 ball to distinguish it from the American game of the same name (8, 9 and 10 ball, etc.)
In the UK and Ireland it is usually called simply “pool”. Blackball is an internationally standardised variation of the popular US type bar and club game eight-ball pool (a.k.a. 8-ball pool or eightball pool), closely related to the originally American and now professionally internationalised game eight-ball.
Official Blackball rules