Something that's raw is uncooked. A ripe raw tomato tastes very different from one that's slowly roasted with olive oil.
Raw food isn't heated, and while raw fruits and vegetables are usually delicious, raw eggs and meat can be dangerous. When you use the word raw to describe things that aren't edible, it generally means "in a natural, untreated state," like raw silk or raw wood. You might also have raw feelings or raw emotions — these are basic and out in the open. The Old English root is hreaw, "uncooked," from a Germanic source.