noun a scale of oxide of iron, formed in forging.
2. clinker ·noun a kind of brick. ·see dutch clinker, under dutch.
3. clinker ·noun a mass composed of several bricks run together by the action of the fire in the kiln.
4. clinker ·noun 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.