Dessicate means to remove moisture from something or to dry it completely. Some synonyms for the word include dehydrate, parch, dry out, wither, and shrivel up. You can use dehydrate if you want to convey the idea of removing all the liquid from something, while parch is a more intense form of dessication that describes something being dried out under intense heat. Dry out suggests that something was once wet or damp and now it is dry. Wither and shrivel up, on the other hand, are more often used in relation to plants or fruits that have lost their moisture and become dry and lifeless.