A composition of lime, water and sand, well mixed into a kind of paste and used for coating walls and partitions of houses. This composition when dry becomes hard, but still retains the name of plaster. Plaster is sometimes made of different materials, as chalk, gypsumand is sometimes used to parget the whole surface of a building.

In pharmacy, an external application of a harder consistence than an ointment, to be spread, according to different circumstances, either on linen or leather. Plaster of Paris, a composition of several species of gypsum dug near Montmartre, near Paris in France, used in building and in casting busts and statues. In popular language, this name is applied improperly to plaster-stone, or to any species of gypsum.