A ceiling was a upwards surface in the interior of a building.
History[]
In a letter sent by the Eleventh Doctor in 2011 to thank a group of humans for saving him and the world, after he told them to look out for him returning to check up on them, he listed a knock on the ceiling that "shouldn't be there" among the things they should look out for. (PROSE: Hello!)
In 2013, the ceiling in Paul Magrs and Jeremy's home, the one between the kitchen and the bathroom, collapsed, sending black muck and dust everywhere. This wasn't the first time this had happened. In Paul and Jeremy's bedroom, there were bookcases that were nearly as tall as the ceiling. At Christmas, they bought a Christmas tree that was so big it easily reached the living room ceiling. In their Beach House, there were piles of books that reached the ceiling. (PROSE: The Story of Fester Cat)