opaque
1. [ adjective ] not clear; not transmitting or reflecting light or radiant energy
Examples:

"opaque windows of the jail" "opaque to X-rays"

Related terms: clear cloudy solid frosted glaucous milk fogged semiopaque unclear opacity
2. [ adjective ] not clearly understood or expressed
Synonyms: unintelligible
Related terms: incomprehensible
Similar spelling:   OPEC