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soft tennis

n. (context sports English) a variant of tennis, developed in Japan, differing in the tennis ball used, from regular tennis (lawn tennis), having a softer rubber ball

Wikipedia
Soft tennis

Soft tennis is a racket game played on a court of two halves, separated by a net. Like regular tennis, it is played by individuals (singles) or pairs (doubles), whose object is to hit the ball over the net, landing within the confines of the court, with the aim of preventing one's opponent from being able to hit it back. Soft tennis differs from regular tennis in that it uses soft rubber balls instead of hard yellow balls.

It is played primarily in Asia, especially in Japan, Taiwan, South Korea, Thailand, and the Philippines. In 2004 soft tennis was introduced into Europe. Belgium, the Netherlands, Poland, Hungary, the Czech Republic and the United Kingdom all now have active soft tennis federations. All of them are also members of the European Soft Tennis Federation, and the International Federation JSTA.