(a.) Incapable of being passed over or surmounted; insurmountable; as, insuperable odds\.

beyond one impassable impenetrable impracticable impractical impregnable incontestable indomitable inexpugnable inoperable insurmountable invincible inviolable invulnerable irresistible overpowering overwhelming resistless too much for unachievable unassailable unattainable unbeatable uncompassable unconquerable undoable uneffectible unnegotiable unperformable unrealizable unsubduable unsurmountable unsurpassable unworkable unyielding