The more I think about it, the more I'm convinced that sumo is not really a sport. No one calls it spootsu anyway -- sumo is and always has been the kokugi (national skill).
OK, one can argue that technique is a big part of sports, but the nuance here is more craft than athletic endeavor. Not to overlook the guts and sweat of it all, but sumo, somehow, remains insular and ritualized -- intricate, mysterious and deceptively layered, like origami.
Suitably, the language of sumo occupies its own particular universe. Wrestlers are rikishi (men of strength), the matches are torikumi and instead of teams they have heya (stables). The manager is called oyakata (father figure) and his wife, who sees to the stable housekeeping, is o-kami-san. The torikumi are held on a sacred circular patch of soil known as the dohyo, closed off by a strand of rope. The referee is a gyoji, or the priest who watches over the dohyo and the rikishi all wear (or wind) mawashi over their prized middles.