What is "swing for the fences"

alt. 1 (context US baseball softball English) To swing at the ball as hard as possible, with the aim of getting a home run, increasing the chance of missing the ball. 2 (context US idiomatic English) To do something extremely ambitious, especially rashly. vb. 1 (context US baseball softball English) To swing at the ball as hard as possible, with the aim of getting a home run, increasing the chance of missing the ball. 2 (context US idiomatic English) To do something extremely ambitious, especially rashly.