sumo

As nouns the difference between sumo and sum

is that sumo is (label) (martial art) while sum is noise (sound or signal generated by random fluctuations).

As nouns the difference between sumo and makunouchi

is that sumo is a stylised Japanese form of wrestling in which a wrestler loses if he is forced from the ring, or if any part of his body except the soles of his feet touches the ground while makunouchi is a Japanese lunch box, usually containing small portions of a variety of foods.

As a proper noun Sumo

is a Misumalpan language of Nicaragua.

As an initialism SUMO

is small ubiquitin-related modifier.