<p><strong>Noun</strong></p><ul><li>A small, black-tipped, fatty mass in a skin follicle, especially of the face; comedo.</li><li>Any of several birds having a head that is black, as the greater scaup, <em>Aythya marila</em>.</li><li>Also called enterohepatitis.</li><li>A malignant, infectious disease of turkeys, chickens, and many wild birds, caused by a protozoan parasite, <em>Histomonas meleagridas</em>, attacking especially the intestines and liver, and often characterized by a darkening of the skin on the head.</li></ul>