Opacity or opaque refers to something difficult to see through or perceive. It can refer to: Opacity (optics), the degree to which light is blocked. Opaque context, a linguistic context in which it isn't possible to substitute co-referential terms while guaranteeing the preservation of truth values. Opaque data, in computer programming, data that can only be manipulated through an external interface, see magic cookie Opaque (restaurant), a restaurant where the dining room is pitch black. - h… (More on Opacity)