The phrase "stained area" refers to a part of the surface that has been marked or discolored by a substance, usually due to spills or accidents. Full definition
For animals whose eyes constantly water and stain the area around the eye. (medi-vet.com)
I stepped in here and cleaned things up a bit, using bleach on the black stained areas before painting the chair with two layers of paint. (oldthingsnewblog.com)
Pre-treat any super stained areas with the spray cleaner, allow it to really soak in... let the foaming action do it's job as you get the cleaner prepared. (onecrazyhouse.com)