Solarium may refer to: Sunroom, a room built largely of glass to afford exposure to the sun. A Terrace (building) or flat housetop. The Solarium Augusti, a monumental meridian line (or perhaps a sundial) erected in Rome by Emperor Augustus.
Noun. 1. cavity wall-a wall formed of two thicknesses of masonry with a space between them. wall-an architectural partition with a height and length greater than its thickness; used to divide or enclose an area or to support another structure; the south wall had a small window; the walls were covered with pictures.
a cavity, hollow, or recess, generally within the thickness of a wall, for a statue, bust, or other erect ornament. hence, any similar position, literal or figurative. Origin: [F., fr. It. nicchia, prop., a shell-like recess in a wall, fr. nicchio a shellfish, mussel, fr.