inenubilable

adjective2

1. •
   (formal, rare) Incapable of being cleared of clouds.

   • Our blue inenubilable Zembla, and the red-capped Steinmann, and the motorboat in the sea cave, and— — 1962
2. •
   (figurative, rare) Inexplicable, mysterious, unclear.

   • For there is nothing in England to be matched with what lurks in the vapours of these meadows, and in the shadows of these spires—that mysterious, inenubilable spirit, spirit of Oxford. — 1911