BLACKHEAD

blackhead, comedo

(noun) a black-tipped plug clogging a pore of the skin

Source: WordNet® 3.1

Etymology

Noun

blackhead (countable and uncountable, plural blackheads)

(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.

(uncountable) A form of histomoniasis in poultry, characterized by cyanotic discoloration on the bird's head.

(countable) A scaup: any of various ducks of the genus Aythya.

Source: Wiktionary

Black"head`, n. (Zoöl.)

Definition: The scaup duck.

Source: Webster’s Unabridged Dictionary 1913 Edition