Atrium/ˈeɪtriəm/ Definition 1 of 2Pro Tip 1/3Architectural Space Refers to a grand open area in large buildings, such as malls or offices. Visitors gathered in the atrium to admire the modern sculpture. Pro Tip 2/3Natural Lighting Often designed with a transparent roof to allow sunlight in, enhancing indoor ambiance. The atrium's glass dome bathed the space in warm sunlight. Pro Tip 3/3Social Hub Acts as a central space for people to meet, relax, or pass through in a building. Meet me in the atrium by the fountain at noon.