im ‧ pass ‧ a ‧ ble /ɪmˈpɑːsəb ə l $ ɪmˈpæ-/ BrE AmE adjective
[ Word Family: noun : ↑ pass , ↑ overpass ≠ ↑ underpass , ↑ passage , ↑ passing ; adjective : ↑ passing , ↑ passable ≠ ↑ impassable ; verb : ↑ pass ]
a road, path, or area that is impassable is impossible to travel along or through:
The mountains are impassable.