constipation: irregular and infrequent or difficult evacuation of the bowels; can be a symptom of intestinal obstruction or diverticulitis
symptom: (medicine) any sensation or change in bodily function that is experienced by a patient and is associated with a particular disease
freeze-drying: a method of drying food or blood plasma or pharmaceuticals or tissue without destroying their physical structure; material is frozen and then warmed in a vacuum so that the ice sublimes