Clinker
Clinker (klink"ẽr) , noun
[From clink; compare Dutch clinker a brick which is so hard that it makes a sonorous sound, from clinken to clink. Compare Clinkstone.]
1.
A mass composed of several bricks run together by the action of the fire in the kiln.
2.
Scoria or vitrified incombustible matter, formed in a grate or furnace where anthracite coal in used; vitrified or burnt matter ejected from a volcano; slag.
3.
A scale of oxide of iron, formed in forging.
4.
A kind of brick. See Dutch clinker, under Dutch.