Define the following terms: - relief - ground - etch

Relief is a sculptural technique where the sculpted elements remain attached to a solid background of the same material. The term relief is from the Latin verb relevo, to raise. To create a sculpture in relief is to give the impression that the sculpted material has been raised above the background plane.
Definition. A ground or primer, is the background surface on which you paint. It is usually a coating such as a gesso primer, which physically separates your painting from the support. It is the foundation of a painting, applied onto the raw canvas, paper, or other support.
In traditional pure etching, a metal (usually copper, zinc or steel) plate is covered with a waxy ground which is resistant to acid. The artist then scratches off the ground with a pointed etching needle where he or she wants a line to appear in the finished piece, so exposing the bare metal.

2.25 because you subtract the two