Definition of "blackhead"

blackhead

noun
countable and uncountable, plural blackheads
1. (countable, medicine) A 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.
  Quotations
  See there! A son is bornAnd we pronounce him fit to fightThere are blackheads on his shouldersAnd he pees himself in the night.
  1972, “Thick As A Brick”, Ian Anderson (lyrics), performed by Jethro Tull
  Wallace sees a cluster of tiny blackheads at the corner of his nose.
  2020, Brandon Taylor, Real Life, Daunt Books Originals, page 215
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.