(1) Characteristic of paper or other substrate that prevents printing on one side from showing through the other side. (2) Characteristic of ink that prevents the substrate from showing through.<br><br>The quality of being opaque. In painting, the power of a pigment to cover or obscure the surface to which it is applied. When opacity is not complete, it can be described as translucence, or as opaque from 99% down to 1%. The equivalent of 0% opacity is transparency.(pr. oh-PA-s&#601;-tee)Also see white lead.