A ball legally free kicked or snapped. It continues in play until the down ends.
any ball that is in play, whether it is a player's possession or not. The ball is live during plays from scrimmage and free kicks, including kickoffs.
as soon as a ball is given to a free-throw shooter or a thrower on a throw-in, it is live, but the game clock does not restart until the ball is alive.
the ball when it is live.
A ball in play or one that bounces exceptionally high.
In baseball, when the ball is alive (or in play), the game can proceed. The pitcher may pitch the ball (if the batter and umpire are ready), the batter may attempt to hit such a pitch, baserunners may attempt to advance at their own risk, and the defense may attempt to put the batter or baserunners out.