Atrium may refer to: Anatomy. Atrium (heart), an anatomical structure of the heart. Atrium, the genital structure next to the genital aperture in the reproductive system of gastropods. Atrium of the ventricular system of the brain. Pulmonary alveolus (also known as atrium alveolus), microscopic air sac in the lungs. Architecture. Atrium (architecture), an open space within a building, either open to the sky or featuring a glass roof. Ancient Roman atrium, a grand entrance hall, reception room, and living room in a traditional Roman house. Specific buildings.
https://en.wikipedia.org/wiki/Atrium