Im‐per″vi‐ous (?), a. [L. impervius; pref. im- not + per through + via way. See Voyage.] Not pervious; not admitting of entrance or passage through; as, a substance impervious to water or air.
This gulf impassable, impervious. Milton.
The minds of these zealots were absolutely impervious. Macaulay.
Syn. — Impassable; pathless; impenetrable; imperviable; impermeable.
— Im‐per″vi‐ous‐ly, adv. — Im‐per″vi‐ous‐ness, n.