From Longman Dictionary of Contemporary Englishinsurmountablein‧sur‧mount‧a‧ble /ˌɪnsəˈmaʊntəbəl◂ $ -sər-/ adjective formal TOO/TOO MUCHan insurmountable difficulty or problem is too large or difficult to deal with The language difference proved an insurmountable barrier.
Examples from the Corpus
insurmountable• Graham overcame seemingly insurmountable transportation barriers to complete his tour.insurmountable barrier• Yet language difficulties have never been insurmountable barriers.• For a start, sheer distance put a well-nigh insurmountable barrier be-tween me and my peers.• Then it seemed that class differences were an insurmountable barrier, but this too was not the only answer.• When it comes to entrepreneurship there are no insurmountable barriers except those we impose on ourselves.• The cost was an insurmountable barrier for many small businesses, and these new business strategies created many side effects.• The railroads overcame what, until then, had been insurmountable barriers of time and distance. 