(Sushi rice for nigiri is called "Shari Dama" meaning sushi rice ball)
What comes to your mind when you hear the word "Sushi"? Would it be a California Roll with crab, avocado or Unagi/Fresh Water Eel Nigiri with sweet Eel Sauce? If that was the case, then, you are only half correct. The word “sushi” refers to vinegared "Sushi Rice," not rolls, not nigiri, not even fish on top of rice. (nor Sashimi, slice of fish for that matter.) The word sushi is said to come from the word “Su-meshi.” “Su” means vinegar and “Meshi” means rice. When abbreviated, it became “sushi.” Therefore, sushi means cooked rice mixed with sushi vinegar. Thus, as long as you uses "sushi rice," it can be called sushi. When Japanese think of sushi, mostly they refer to Nigiri. In America, most people think of Rolls. There are many different types of sushi from rolls to pressed sushi using both fish and vegetables. Here are some example of different type of sushi:
Maki Sushi (pronounced as makizushi) - Rolled sushi with ingredients inside
Nigiri Sushi (pronounced as Nigirizushi) - Sliced ingredient on top of ball of rice.
Temaki Sushi (temakizushi) - Ice cream cone shaped hand roll.
Sashimi - Means sliced meat, not Sushi. Can be either fish, meat and vegetables.
Oshi Sushi (pronounced as Oshizushi) - pressed sushi,