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 brigh…t; dark; dull..
4. hard to understand; not clear or lucid ; obscure: The problem remains opaque despite explanations. .
5. dull, stupid, or unintelligent..
Bencon . (MORE)