Adjective: unsurmountable ,ún-su(r)'mawn-tu-b(u)l
- Not capable of being surmounted or overcome
"unsurmountable disadvantages";
- insurmountable
- Incapable of being surmounted or climbed
"The sheer cliff face proved unsurmountable for the novice climbers";
- unclimbable
See also: impassable, impossible, insuperable, unconquerable, unpassable