Vintage milk glass lamp or light shade or globe. It has a pretty swirl pattern, the opening is 1 1/2" on one side and about 3/4" on the other. It is 4 1/4" tall and about 6 1/2" wide.
It is in nice condition, the dark area around the larger opening is from the metal of the lamp and would probably come off. I only used water and a mild cleaner prior to listing.