klinker

noun10

1. •
   A mass of bricks fused together by intense heat.
2. •
   Slag or ash produced by intense heat in a furnace, kiln or boiler that forms a hard residue upon cooling.

   • The coal was terrible stuff—Indian, Abdul told me. The "dart" was used often and I saw some monster clinkers. — 1942
3. •
   An intermediate product in the manufacture of Portland cement, obtained by sintering limestone and alumino-silicate materials such as clay into nodules in a cement kiln.
4. •
   Hardened volcanic lava.

   • This wall of rock, which had no doubt once formed the lip of the crater, was about a mile and a half thick, and still covered with clinker. — 1886
5. •
   A scum of oxide of iron formed in forging.
6. •
   [before a noun] A style of boatbuilding using overlapping planks.
7. •
   (slang) A mistake or blunder.
8. •
   A very hard brick used for paving customarily made in the Netherlands.

   • She left the road at the little shed where he whom she still regarded as her father used to keep his tricycle, and walked up the clinker path towards the house. — 1938
9. •
   Someone or something that clinks.
10. •
    [in the plural] Fetters.