1. Descriptive of any game in which the object balls must be struck in numerical order. Billiard researcher Mike Shamos observes that it would be more intuitive to call such games "'series' or 'sequence'". The term actually derives from the set-up of the game Chicago, in which the balls are not racked, but placed numerically around the table along the cushions (and must to be shot in ascending order). Other common rotation games include pool (obviously), nine-ball, seven-ball, ten-ball
2. The specific pool game of rotation.