The upper interior surface of a room. Material used to cover this surface. Something resembling a ceiling: a ceiling of leaves over the arbor. An upper limit, especially as set by regulation: wage and price ceilings. The highest altitude under particular weather conditions from which the ground is still visible. The altitude of the lowest layer of clouds. The maximum altitude that an aircraft can reach under a given set of conditions, such as a minimum rate of climb. Nautical The planking applied to the interior framework of a ship.