deck that forms the roof of a cabin built in the aft part of the superstructure of a ship
A poop deck is part of a ship. It is the deck that is the roof of a cabin. It is at the back of a ship. Usually, it is the highest deck. Note that poop comes from Frenchpoupe, Latinpuppis, which is the name of the stern of a ship.
The lit part is the poop deck on a model of a ship.
Horace Vernet: Episode from the Mexico expedition, 1838: The Prince of Joinville on the poop of the corvette Créole listens to the report from the vessel's Lieutenant, Penaud, and sees the explosion of the tower of the Fort of Saint-Jean d'Ulloa on 27 November 1838. The frigate Gloire can be seen in the background.