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 is not 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. - http://www.darkdining.com/
- Opaque travel inventory, the market of selling unsold travel inventory at a discounted price.