INTRADOSSO (from Fr. *intrados*). — Technical term in architecture, meaning “soffit,” designating the inner, curved surface of arches and vaults.
The shape of the intrados curve determines the classification of arches, which are termed:
— semicircular, when the curve is a semicircumference whose chord is the horizontal diameter passing through the springing;
— segmental, when the curve is not a semicircumference or is a polygonal line with the center of the central curve segment below the level of the springing;
— pointed, when the intrados curve is formed by two arcs of a circumference meeting at a vertex and having their centers, as a rule, at two-thirds of the span;
— stilted, when the center of the curve lies below the springing lines.
A particular form of intrados curve is found in ogee and keel arches, which are infrequently used in architectural practice.
Another type of intrados is the lobed intrados, characteristic of Islamic architecture (e.g., the church of the Corpus Christi in Segovia and the mosque of Córdoba).