insuperable

adjective2

1. •
   Impossible to achieve or overcome or be negotiated.

   • While Indian English may not have a uniform standard form throughout the country, this in itself is not an insuperable obstacle for lexicography. — 2012
2. •
   Overwhelming or insurmountable.

   • For the first time I steadily reviewed the obstacles—and to consider them was at once to see they were insuperable. — 1834