impassable 10 Associations

unpassable unsurmountable (similar term) unclimbable (similar term) unnavigable (similar term) untraversable (similar term) passable (antonym)

insuperable 11 Associations

unconquerable insurmountable (similar term) unsurmountable (similar term)

unconquerable 13 Associations

insuperable insurmountable (similar term) unsurmountable (similar term)

unpassable 10 Associations

impassable unsurmountable (similar term) unclimbable (similar term) unnavigable (similar term) untraversable (similar term) passable (antonym)