noun a white to gray volcanic tufa, formed of decomposed trachytic cinders;
sometimes used as a cement. hence, a coarse sort of plaster or mortar, durable in water, and used to line cisterns and other reservoirs of water.
noun a white to gray volcanic tufa, formed of decomposed trachytic cinders;
sometimes used as a cement. hence, a coarse sort of plaster or mortar, durable in water, and used to line cisterns and other reservoirs of water.
Webster English vocab. Английский словарь Webster. 2012