impassable Copy link Outline 1. insŭpĕrābĭlis2. invius (strictly, without paths)3. impervius4. more freq. expr. by verb • impassable: 1. insŭpĕrābĭlis: that route was absolutely i., ea vero via ins. fuit, Liv. 21, 36. 2. invius (strictly, without paths): a region i. for rocks, regio rupibus inv., Plin. 12, 14, 30: Virg.: v. pathless. 3. impervius: i. roads, [interrupta et] imp. itinera, Tac. A. 3, 31: Ov. 4. more freq. expr. by verb: a river i. on foot, except in one place, flumen quod uno omnino loco pedibus transiri potest, Caes. B. G. 5, 18: v. to cross. Phr.: (almost) i. woods, impeditissimae silvae, Hirt. B. G. 8, 18: Caes.