From Longman Dictionary of Contemporary Englishinsuperablein‧su‧pe‧ra‧ble /ɪnˈsjuːpərəbəl◂ $ ɪnˈsuː-/ adjective formal IMPOSSIBLEan insuperable difficulty or problem is impossible to deal with There were insuperable obstacles, and the plan was abandoned. As usual, the hero was facing insuperable odds.
Examples from the Corpus
insuperable• The legal barriers are presently insuperable.Origin insuperable (1300-1400) French Latin, from superare “to get over”, from super “above” 