Wiffle ball          
noun US trademark (also Whiffle ball) uk/ˈwɪf.əl ˌbɔːl/ us/ˈwɪf.əl ˌbɑːl/
 [ C ]威浮球 
a light plastic ball with holes in it
  The game is played with a Wiffle ball, which moves rather slowly and not always in a straight line. 比赛用的是威浮球,其移动速度比较慢,而且不一定是直线移动。 
  [ U ]打威浮球,威浮比赛 
a game similar to baseball played in the US using a long, light plastic bat and a Wiffle ball
  When we were kids we used to play Wiffle ball in the backyard. 我们小时候经常在后院玩威浮球。 
 - More examples
 - Davis bought a Wiffle ball and helped his son work on his batting technique.
 - Back yards at the new homes are barely big enough for a Wiffle ball game.
 - The yard worked perfectly as a football field, Wiffle Ball diamond, wrestling ring, etc.
 - I said to him, let's go play some whiffle ball. So we got the Whiffle ball and bat and went to the park.