Definition of "fuligin"

Then the Forestal took the Staff of Law, black as fuligin after her battle - -

2013, Stephen Donaldson, The Last Dark. The Last Chronicles of Thomas Covenant

“What is the tinct of your own guild?” “Fuligin,” I told him. “The color that is darker than black.”

1980, Gene Wolfe, chapter VI, in The Shadow of the Torturer (The Book of the New Sun; 1), New York: Simon & Schuster, page 57

“I'm wearing black only until I find something darker.” — “Fuligin, Mark. Fuligin.”

2001, “Richard Horton” (username), “REVIEW: Vernor Vinge’s ‘Across Realtime’”

More like fuligin: darker than an event horizon.

2003, “Mike Andrews” (username), “hosteurope blackhat?”

The shadow hovers o’er us, old and long,Its power fuligin and vast.

1986, Julia Ecklar, Terminus Est