1. Non-Europeans, in particular, may find the entire topic impenetrably abstruse.

2. Standing against the gloomy and impenetrably dark background, the phantasm in the picture is colourful and magnificent.

3. There was a faint shimmer of light in the hall, but the study doorway yawned impenetrably black.

4. 13 Writing in an impenetrably mystical Hebrew, Kook tried to disprove the traditionalists' view of Zionism as heresy.

5. The refrain "The answer, my friend, is blowin' in the wind" has been described as "impenetrably ambiguous: either the answer is so obvious it is right in your face, or the answer is as intangible as the wind".