A fast Bajoran court sport, something like handball played with padded gloves in a walled court, which Kira Nerys follows keenly and plays in the holosuites of Deep Space 9.
Springball is a popular Bajoran sport played by two opponents in an enclosed court. The players wear protective gear and strike a small ball against the walls with their hands, and the game is quick and physical enough for collisions to be part of it.
It is first discussed in Shadowplay, when Vedek Bareil visits the station and Kira is surprised to learn that the mild-mannered cleric is a keen player. Their shared enthusiasm is one of the things that brings the two together.
A match is seen on screen in For the Cause, where Kira plays in a holosuite court in front of spectators. The game is mentioned on other occasions as her usual way of working off the frustrations of the job.