But surely it would feel more protected by an opaque wall and a small window.

It turned out to be an opaque but glowing wall.

Below him was a section of a room, whose limits he could not see because the opaque walls barred his vision on either side.

On the distant horizon behind them, perhaps 60 miles away, was a dark, opaque wall.

He could not see the actual ground because there was an opaque wall of sand between.

But they are cut off from one another by opaque walls.

She completed the course without difficulty and came at last to the opaque wall.

The three operating rooms are over 80 years old, and one of them has an opaque wall of glass bricks.

More and more, these writers felt an opaque wall across the future.

But there's no sky, no stars, just the opaque blank wall next door.