plaster of Paris, plaster - any of several gypsum cements; a white powder (a form of calcium sulphate) that forms a paste when mixed with water and hardens into a solid; used in making molds and sculptures and casts for broken limbs --2is a kind ofcalcium sulphate, calcium sulfate --2has substances: gypsum
poultice, cataplasm, plaster - a medical dressing consisting of a soft heated mass of meal or clay that is spread on a cloth and applied to the skin to treat inflamed areas or improve circulation etc. --3is a kind ofdressing, medical dressing --3has particulars: mustard plaster, sinapism