noun.
A device used to print photographs and illustrations with borders that fade gradually into the background.
noun.
One who makes or specializes in the making of vignettes.
The Century Dictionary and Cyclopedia
noun.
In photography, any device for causing the edges of a printed part of a negative to fade away evenly and gradually into the background
the GNU version of the Collaborative International Dictionary of English
noun.
A device used by photographers in printing vignettes, consisting of a screen of paper or glass with a central aperture the edges of which become opaque by insensible gradations.