CLINKER, in industry, the common name for coal residues which are formed in lumps, partly fused, in grates or furnaces. Such clinker is used for many purposes as a raw material, and is a useful matrix for inferior Portland cement concrete. The name is also applied to the fused masses of brick which occur in brick ovens.
What is really a different word, but with the same spelling, is derived from clinch, or clench, a common Teutonic word, meaning to "fasten together." This word appears in the form "clinker built" as distinguished from "carvel-built" for a boat whose strakes overlap and are not fastened "flush."