What is a horizontal ledge on the face of a wall, formed by a diminution of its thickness, or by the weathering or upper surface of a part built out from it; -- called also set-off called?

offset — (Arch.) A horizontal ledge on the face of a wall, formed by a diminution of its thickness, or by the weathering or upper surface of a part built out from it; -- called also set-off. (Webster's 1913.)

Sources