/blak"hed'/ , n.
1. a small, black-tipped, fatty mass in a skin follicle, esp. of the face; comedo.
2. any of several birds having a black head, as the greater scaup, Aythya marila.
3. Also called enterohepatitis . Vet. Pathol. a malignant, infectious disease of turkeys, chickens, and many wild birds, caused by a protozoan parasite, Histomonas meleagridas, attacking esp. the intestines and liver, and often characterized by a darkening of the skin on the head.
[ 1650-60; BLACK + HEAD ]