Lewis Short
(adjective) : ĭn-exsŭpĕrābĭlis (inexup-), e
* That cannot be crossed or passed over, insurmountable (a favorite word with Livy).
* Lit.: Alpes,Liv. 5, 34, 6: ripa,id. 44, 35, 8: serrae,id. 21, 30, 7: manu,Vell. 2, 32, 4; cf. id. 2, 120, 2.—Comp.: inexsuperabilior saltus fuit,Liv. 36, 17, 3.
* Trop.: vis fati,unconquerable, invincible,Liv. 8, 7, 8: bonum,unsurpassable,Sen. Ep. 85.—Plur. as subst.: inexsuperabilibus vim afferre,to overcome impossibilities,Liv. 38, 20, 8.
Charlton T. Lewis, Charles Short, A Latin Dictionary