1. 不能穿过的;刺不进的;透不过的
If you describe something such as a barrier or a forest as impenetrable, you mean that it is impossible or very difficult to get through.
e.g. ...the Caucasus range, an almost impenetrable barrier between Europe and Asia.
高加索山脉,几乎难以穿越的欧亚屏障
2. 费解的;难以理解的
If you describe something such as a book or a theory as impenetrable, you are emphasizing that it is impossible or very difficult to understand.
e.g. His books are notoriously impenetrable.
他的书出了名的晦涩难懂。
e.g. ...these impenetrable poems.
这些隐晦难懂的诗
impenetrably...impenetrably detailed reports on product sales.
详细得令人费解的产品销售报告