Plaster is a building material that's applied as a wet paste and dries very hard and smooth. The walls inside your house might be made of plaster.

New houses typically have interior walls made of drywall, rather than plaster, but older homes usually have many plaster surfaces. Plaster starts as a mixture of lime, gypsum, sand, or cement that's mixed with water. This soft substance is applied to surfaces where it hardens — either for walls, works of art, or as casts used to hold broken bones steady. In Britain, a plaster is also a sticky bandage, while an American would call this a Band-Aid.

Definitions of plaster
  1. noun
    a mixture of lime or gypsum with sand and water; hardens into a smooth solid; used to cover walls and ceilings
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    finish coat, finishing coat
    the final coating of plaster applied to walls and ceilings
    a thin mortar that can be poured and used to fill cracks in masonry or brickwork
    parget, pargeting, pargetting
    plaster used to coat outer walls and line chimneys
    a coarse plaster for the surface of external walls
    spackle, spackling compound
    powder (containing gypsum plaster and glue) that when mixed with water forms a plastic paste used to fill cracks and holes in plaster
    a plaster now made mostly from Portland cement and sand and lime; applied while soft to cover exterior walls or surfaces
    a substance similar to stucco but exclusively applied to masonry walls
    type of:
    (chemistry) a substance consisting of two or more substances mixed together (not in fixed proportions and not with chemical bonding)
    covering material
    a material used by builders to cover surfaces
  2. noun
    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
    synonyms: plaster of Paris
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    gypsum or plaster of Paris spread on a surface to make it suitable for painting or gilding (or a surface so prepared)
    type of:
    calcium sulfate, calcium sulphate
    a white salt (CaSO4)
  3. noun
    a surface of hardened plaster (as on a wall or ceiling)
    “there were cracks in the plaster
    synonyms: plasterwork
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    pargeting, pargetry, pargetting
    ornamental plasterwork
    type of:
    the outer boundary of an artifact or a material layer constituting or resembling such a boundary
  4. verb
    coat with plaster
    synonyms: daub
    apply to a surface
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    cover with two coats of plaster
    apply ornamental plaster to
    apply roughcast to
    plaster with mud
    plaster with mortar
    type of:
    coat, surface
    put a coat on; cover the surface of; furnish with a surface
  5. verb
    cover conspicuously or thickly, as by pasting something on
    “The demonstrators plastered the hallways with posters”
    synonyms: beplaster
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    type of:
    provide with a covering or cause to be covered
  6. verb
    apply a heavy coat to
    synonyms: plaster over, stick on
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    type of:
    provide with a covering or cause to be covered
  7. verb
    affix conspicuously
    “She plastered warnings all over the wall”
    cover conspicuously or thickly, as by pasting something on
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    type of:
    affix, stick on
    attach to
  8. noun
    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.
    synonyms: cataplasm, poultice
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    mustard plaster, sinapism
    a plaster containing powdered black mustard; applied to the skin as a counterirritant or rubefacient
    type of:
    dressing, medical dressing
    a cloth covering for a wound or sore
  9. noun
    adhesive tape used in dressing wounds
    synonyms: adhesive plaster, sticking plaster
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    court plaster
    a plaster composed of isinglass on silk; formerly used to dress superficial wounds
    type of:
    adhesive tape
    tape coated with adhesive
  10. verb
    dress by covering with a therapeutic substance
    synonyms: poultice
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    type of:
    apply a bandage or medication to
  11. verb
    apply a plaster cast to
    plaster the broken arm”
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    type of:
    provide with a covering or cause to be covered
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