a small, black-tipped, fatty mass in a skin follicle, especially of the face; comedo.
any of several birds having a black, head, as the greater scaup, Aythya marila.
Also called enterohepatitis. Veterinary Pathology. a malignant, infectious disease of turkeys, chickens, and many wild birds, caused by a protozoan parasite, Histomonas meleagridas, attacking especially the intestines and liver, and often characterized by a darkening of the skin on the head.