The Collaborative International Dictionary
Inexsuperable
Inexsuperable \In`ex*su"per*a*ble\, a. [L. inexsuperabilis; pref. in- not + exsuperabilis that may be surmounted. See In- not, Ex-, and Superable.] Not capable of being passed over; insuperable; insurmountable.
Wiktionary
inexsuperable
a. (context archaic English) Not capable of being passed over; insuperable; insurmountable.