Rule 2 – Section 6 – BATTED BALL
2-6-1 A batted or thrown ball is in flight until it has touched the ground or some object other than a fielder.
2-6-2 A fly ball is a batted ball which rises an appreciable height above the ground.
2-6-3 A line drive is a batted ball which travels parallel, or nearly so, with the ground through most of its flight.
2-6-4 A ground ball is one which is neither a fly nor a line drive.