\^▐blaŋk-^▐fiks\ n [F] (1866) A synthetic form of barium sulfate prepared by reacting aqueous solutions containing barium ions with others containing sulfate ions and precipitating the reaction product. It is used as a special-purpose filler to impart X ray opacity and high specific gravity. Precipitated barium sulphate is used as a semi-transparent extender in printing inks.