noun[ U ]sportsspecializeduk/ˈʌn.də.spɪn/us/ˈʌn.dɚ.spɪn/
（球）下旋
the movement of a ball turning round very quickly in the air or on a surface so that the ball slows down or moves backwards after landing or hitting something
She puts underspin on the ball all the time.她总是在球上加下旋。
He hit his forehands with underspin, then overspin.
更多例句
Brush the back of the ball downward for underspin.
A stroke with underspin is the most dangerous passing shot, since the underspin causes the ball to rise.
She throws in the front-of-the-hand balls, with underspin or overspin.