Something that's shriveled is wrinkled, withered, and dried out. If you forget to water your plants, they will become shriveled.
Our skin becomes more shriveled as we grow older, and if you leave a bowl of apples on your table for weeks, the fruit will eventually become shriveled as well. To shrivel is to contract, or grow smaller, and wrinkle. The origin of both words is uncertain, but it's suspected that they have a Scandinavian root, since skryvla means "to wrinkle" in Swedish. Other guesses connect shriveled with shrimp or shrink.