Webster's Revised Unabridged Dictionary · 1913

Fusain

Fusain , noun

[French, the spindle tree; also, charcoal made from it.]

(a)
(Fine Arts) Fine charcoal of willow wood, used as a drawing implement.
(b)
(Fine Arts) A drawing made with it. See Charcoal, n. 2, and Charcoal drawing, under Charcoal.