pol·yp / ˈpäləp/ • n. 1. Zool. a solitary or colonial sedentary form of a coelenterate such as a sea anemone, typically having a columnar body with the mouth uppermost surrounded by a ring of tentacles. In some species, polyps are a phase in the life cycle that alternates with a medusoid phase. Compare with medusa.2. Med. a small growth, typically benign and with a stalk, protruding from a mucous membrane.DERIVATIVES: pol·yp·ous / ˈpäləpəs/ adj. (in sense 2).

polyp (polypus) (pol-ip) n. a growth, usually benign, protruding from a mucous membrane. Polyps are commonly found in the nose and sinuses, giving rise to obstruction, chronic infection, and discharge. Other sites include the ear, the stomach, and the colon, where they may eventually become malignant. Polyps are usually removed surgically (see polypectomy). juvenile p. a polyp that occurs in the intestine (usually colon or rectum) of infants or young people; sometimes they are multiple (see polyposis). Most juvenile polyps are benign. See also Peutz-Jeghers syndrome.

polyp The sedentary stage in the life cycle of the Cnidaria, consisting of a cylindrical body fixed at one end to a firm base and having a mouth surrounded by a ring of tentacles at the other. Some polyps (e.g. Hydra) are single; others (e.g. the corals and Obelia) form colonies. Polyps typically reproduce asexually by budding to form either new polyps or medusae. The latter reproduce sexually giving rise to new polyps. Sea anemones are solitary polyps that reproduce sexually to form new polyps.

polyp The soft-bodied, usually sedentary form of Cnidaria, consisting of a cylindrical trunk which is fixed at one end, with the mouth surrounded by tentacles at the other end. In Siphonophora the polyp has been modified for a pelagic, colonial existence.

polyp Body type of various species of animal within the phylum Cnidaria. It has a mouth surrounded by extensible tentacles, and a lower end that is adapted for attachment to a surface. It is distinct from the free-swimming medusa. It may be solitary, as in the sea anemone, but is more often an individual of a colonial organism such as coral.