An architraves is a strip of wood (usually) or moulding surrounding a door or window frame, covering the join between the frame and the plaster or other surface finish of the surrounding wall. Architraves are usually made of wood but other materials such as plaster, MDF or UPVC are also used.
Architraves provide a decorative finish to doorways but do not have any structural function. They are therefore unlikely to be a significant item on a survey report. Replacing damaged timber architraves can generally be done easily; repairing or replacing architraves in period properties may require an expert craftsman, but specialist companies provide a wide range of architrave mouldings in period designs.
(in classical architecture, an architrave is a stone beam or lintel resting on two columns.)