CEILING, in architecture, the top or roof of a lower room; or a covering of plaster, over laths nailed on the bottom of the joists that bear the floor of the upper room; or where there is no upper room, on joists for the purpose; hence called ceiling joists. The word ceiling answers pretty accurately to the Latin laternar, "every thing over head."
Plastered ceiling, are much used in Britain, more than in any other country: nor are they without their advantages, as they make the room lightsome; are good in case of fire; stop the passage of the dust; lessen the noise over head; and, in summer, make the air cooler.