noun A very hard brick used for paving customarily made in the Netherlands. .mw-parser-output .defdate{font-size:smaller}
noun A mass of bricks fused together by intense heat.
noun Slag or ash produced by intense heat in a furnace, kiln or boiler that forms a hard residue upon cooling.
noun 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.