- n the quality of being impenetrable (by people or light or missiles etc.)
- n incomprehensibility by virtue of being too dense to understand
- Other yeggs scowled at the thought of having to add to their equipmentjimmy, "soup" (nitroglycerin), oxyacetylene blowtorch a gas mask of exceedingly high impenetrability.
- At first it seems a small joke in reference to Bohr's logorrheaic writings, whose impenetrability became legendary.
- He was quite clear about what he wanted to avoid: out-of-date talk and learned impenetrability in general.