insuperable
1. [ adjective ] impossible to surmount
Synonyms: insurmountable
Related terms: unconquerable
2. [ adjective ] incapable of being surmounted or excelled
Synonyms: unconquerable
Examples:

"insuperable odds" "insuperable heroes"

Related terms: insurmountable
Similar spelling:   insuperably
  insufferable
  insupportable
  inseparable
  inescapable