What is "horsehair worm"

Horsehair \Horse"hair`\, n. A hair of a horse, especially one from the mane or tail; the hairs of the mane or tail taken collectively; Specifically: a black shiny fabric made of such hairs, used commonly in the 1800's as a covering for stuffed furniture such as chairs and couches.

Horsehair worm (Zo["o]l.), the hair worm or gordius.

n. Any of the Nematomorpha.