The quality of being insuperable or insurmountable; insuperability.(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "insuperableness" in a sentence
"It needed but an hour's talk to convince me that I had met two of the most intellectual artists in the dramatic profession, and also to learn how great were the obstacles which lay in the way of producing a real play, each year adding to the insuperableness of the barriers."