1) Drywall 2) Sheetrock 1) Gypsum board 2) Wallboard 
Plasterboard is a type of building board composed of a layer of gypsum on either side of which is affixed a layer of very stout paper or fibre.
[n] - wallboard with a gypsum plaster core bounded to layers of paper or fiberboard
A 'sandwich' of plaster with paper/card on either side. Widely used for ceilings and walls etc.
Prefabricated sheets of plaster for walls and ceilings
Prefabricated sheets of plaster for ceilings and walls.
gypsum board noun wallboard with a gypsum plaster core bounded to layers of paper or fiberboard; used instead of plaster or wallboard to make interior walls