What is sumo?

Actually, sumo, in Chinese is called "相撲"。

Sumo (相撲, sumō?) is a competitive contact sportwhere a wrestler(rikishi) attempts to force another wrestler out of a circular ring (dohyō) or to touch the ground with anything other than the soles of the feet.

More can be seen on this website︰http://en.wikipedia.org/wiki/Sumo

Chinese can be seen on this website︰http://zh.wikipedia.org/wiki/%E7%9B%B8%E6%92%B2

Acknowledgement : Wikipedia