2. Regarding something which does not allow light to pass through: The windows were painted black so they would be opaque, thus permitting the photographer to work in his photo-processing laboratory without unwanted illumination.
2. Characteristic of something self-evident; obvious; apparent: Trina's facial expression was so transparent that Susan always knew what she was thinking.
The information from the lecture was completely opaque to Ryan and so he couldn't understand a thing.
After Howard read the text book, his mind felt more translucent, as if some light on the subject was getting through and the information was beginning to make sense, but not completely.
Then, after Marla asked for an explanation, the answer suddenly became transparent.