—adj. 1. not transparent or translucent; impenetrable to light; not allowing light to pass through.
2. not transmitting radiation, sound, heat, etc.
3. not shining or bright; dark; dull.
4. hard to understand; not clear or lucid; obscure: The problem remains opaque despite explanations. 5. dull, stupid, or unintelligent.
—n. 1. something that is opaque.
2. Photog.a coloring matter, usually black or red, used to render part of a negative opaque.
—v.t. 1. Photog.to cover up blemishes on (a negative), esp. for making a printing plate.
2. to cause to become opaque.