adj. 25B6; adjective
he seemed impervious to the chill wind : UNAFFECTED, untouched, immune, invulnerable, insusceptible, resistant, indifferent, heedless, oblivious; proof against.
an impervious damp-proof course : IMPERMEABLE, impenetrable, impregnable, waterproof, watertight; (hermetically) sealed.
susceptible, permeable.