Soffit (from French soffite, Italian soffitto, formed as a ceiling; from suffictus for suffixus, Latin suffigere, to fix underneath).

A soffit, in architecture, describes the underside of any construction element, for instance, the underside of an arch or architrave (whether supported by piers or columns), the underside of a flight of stairs, under the classical entablature or the underside of the projecting cornice.

In modern architecture, a soffit can be installed on the underside of a ceiling to fill the space above the kitchen cabinets, at the corner of the ceiling and wall. Typically made from gypsum wallboard, over 2x4 studs, the soffit is also made from a wide range of Building materials.

References

Ceilings

Soffite