D defs.my
Entry 1 sense Webster, 1913

Portland cement

/pôr'-tlənd səm-ĕnt'/ · Port·land ce·ment · IPA
01 A cement having the color of the Portland stone of England, made by calcining an artificial mixture of carbonate of lime and clay, or somet…
  1. 1.
    A cement having the color of the Portland stone of England, made by calcining an artificial mixture of carbonate of lime and clay, or sometimes certain natural limestones or chalky clays. It contains a large proportion of clay, and hardens under water.