A prune is a dried plum of any cultivar, mostly Prunus domestica or European Plum. The use of the term for fresh fruit is obsolete except when applied to varieties grown for drying.
Basic Nutrition. One cup of prunes, or dried plums, has 418 calories, 3.8 grams of protein, .6 grams of total fat and 111 gram of total carbohydrates. Prunes deserve their reputation as a laxative because a 1-cup serving has 12 grams of dietary fiber.