Matt - What does matt mean?

Definition of MATT:

A type of finish. Matt (sometimes spelled matte) is used to describe a surface or colour that is dull and non-shiny. A matt surface diffuses light; when light is reflected off a matt surface it is spread out over a wide area, which creates a flat, non-glossy finish. In labelling, coatings, face materials, and inks with matt finishes can be used to create a label with a matt finish.