What do Sheer Wall and Spandrel mean in architecture?

(I think it is spelled Shear Wall)

1. Stress that is diagonal may be exerted on a building due to events such as earthquakes, wind or explosions. In order to resist shear stress walls along the plane of the anticipated stress are stiffened. In wood frame construction stiffening is often done by sheathing the studs with plywood. A wall might also be stiffened with other material such as plaster.Structural value is determined by calculating the shear resistance values along each plane for the entire structural system.

2. Wall which is designed to add stiffness to a stud wall so that it can resist sideways or horizontal loads by mounting plywood sheathing from the bottom plate to the top plate and nailing it in place as shown by the shear schedule in the plans.

3. In structural engineering, a braced wall line or shear wall is a wall composed of braced panels (also known as shear panels) to counter the effects of lateral loads acting on a structure. Wind and earthquake loads are the most common loads braced wall lines are designed to counteract. Under several building codes including the International Building Code and Uniform Building Code, all exterior wall lines in wood or steel frame construction must be braced.

SPANDREL:

1. space between one arch and another: the triangular space between the right or left exterior curve of an arch and the framework of another arch

2. space between two arches and cornice: the area between two arches and a horizontal cornice above them