The scaup duck.
- Medicine A plug of keratin and sebum within a hair follicle that is blackened at the surface. Also called comedo.
- An infectious disease of turkeys and some wildfowl that is caused by a protozoan (Histomonas meleagridis) and results in lesions of the intestine and liver. Also called enterohepatitis, histomoniasis, infectious enterohepatitis.
- Any of various birds, such as the scaup, with dark head markings.