​ POLYPUS, a term signifying a tumour which is attached by a narrow neck to the walls of a cavity lined with mucous membrane. A polypus or polypoid tumour may belong to any variety of tumour, either simple or malignant. The most common variety is a polypus of the nose of simple character and easily removed. Polypi are also met with in the ear, larynx, uterus, bladder, vagina, and rectum. (See Tumour.)