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shot clock

n. (context basketball English) A timer measuring the length of time since the last shot.

Wikipedia
Shot clock

A shot clock is used in some sports to quicken the pace of the game. It is normally associated with basketball, but is also used in snooker, pro lacrosse, water polo, korfball, and ten-pin bowling. It is analogous with the play clock used in American and Canadian football.

In basketball, the shot clock is a timer designed to increase the game's pace (and scoring levels). The offensive team must attempt a field goal with the ball leaving the player's hand before the shot clock expires and either touching the rim or entering the basket. If the offensive team fails to register a field goal attempt within the time limit, they are assessed a violation resulting in a turnover to their opponents; if the ball hits or enters the rim after the clock expires, it is not a violation so long as it left the player's hand before expiration. The maximum time limit of the shot clock varies by level of play and league: The National Basketball Association has had a 24-second limit since first introducing the clock in the 1950s; and college basketball for both men and women has a 30-second limit. The WNBA had a 30-second clock originally; since 2006 the limit is 24 seconds.