A usually exophytic mass attached to the underlying tissue by a broad base or a thin stalk. Polyps can be neoplastic or non-neoplastic. Neoplastic polyps usually represent proliferations of the epithelium, and are commonly seen in the gastrointestinal tract. Polyps of the gastrointestinal tract are often called adenomas, are associated with dysplasia, and may eventually transform into carcinomas. Non-neoplastic polyps may be inflammatory, degenerative, or the result of malformations. [from
NCI]