From Latin ātrium, the soot-darkened central hall of a Roman house, later adopted for modern open-plan architecture and heart anatomy.
An open central hall or court in an ancient Roman house, or a large open space within a modern building, often with a glass roof.
From Latin ātrium, the central open area in a Roman house where the hearth fire burned and smoke escaped through a hole in the roof. The word may derive from āter 'black, dark' because the walls were blackened by soot. Anatomists borrowed it in 1870 for the upper chambers of the heart. Key
The Roman atrium had a rectangular opening in the roof called the compluvium and a shallow pool below called the impluvium to catch rainwater—an elegant passive cooling and water collection system.