Sashimi is a Japanese delicacy. It primarily consists of very fresh raw seafood, sliced into thin pieces, and served with only a dipping sauce (soy sauce with wasabi paste or such condiments as grated fresh ginger, or ponzu), and such garnishes as shiso and shredded daikon radish. Dimensions vary but are typically about 2.5 cm (1") wide by 4 cm (1.5") long by 0.5 cm (0.2") thick.
The word sashimi means "pierced body", This word had used from Muromachi period, withheld the word Cut, the culinary step, by Samurai for inauspiciousness. This word may derive from the culinary practice of sticking the fish's tail and fin to the slices in identifying the fish being eaten.
Another possibility for the name could come from the traditional method of harvesting. 'Sashimi Grade' fish is caught by individual handline. As soon as the fish is landed, its brain is pierced with a sharp spike; and it is placed in slurried ice. This spiking is called the Ike jime process. The flesh contains minimal lactic acid because it died instantly so it will keep fresh on ice for about ten days, without turning white or otherwise degrading.
Source: http://en.wikipedia.org/wiki/Sashimi; Nov 9, 2010