blackheads

Noun

blackhead (countable and uncountable, plural blackheads)

1. (countable) A type of comedo, a skin blemish, a type of acne vulgaris, where a pore becomes clogged with a dark, hard, cheesy keratin-filled substance forming a hard black "head" on the skin's surface.
   • See there! A son is born
     And we pronounce him fit to fight
     There are blackheads on his shoulders
     And he pees himself in the night.1972, “Thick As A Brick”, Ian Anderson (lyrics), performed by Jethro Tull

   Synonyms:

   open comedo

2. (uncountable) A form of histomoniasis in poultry, characterized by cyanotic discoloration on the bird's head.
3. (countable) A scaup: any of various ducks of the genus Aythya.