unimpenetrable

comparative more unimpenetrable · superlative most unimpenetrable

1. archaicSynonym of impenetrable.

   Trees and shrubs growing on the muddy shores, where they form almost unimpenetrable barriers on low coasts.

   1886, Frank S. Plant, Notes on the Philippines, page 45

   1 more example

   Those whom he most persecuted with his despatches were Sir John Burgoyne, Lord Panmure, Lord Palmerston, Sir George Grey, and that ancient and unimpenetrable tribune, the commissioners of Chelsea Hospital.

   1859, Thomas William J. Connolly, The Romance of the Ranks, page 357

   Synonyms: impenetrable