adjective. Incapable of being penetrated.

adjective. Incapable of being affected.

Not pervious; not to be passed through or penetrated; impermeable; impenetrable: as, a substance impervious to moisture.

Synonyms Impenetrable, impassable, pathless.

adjective. Not pervious; not admitting of entrance or passage through.

adjective. unaffected or unable to be affected by

adjective. preventative of any penetration; impenetrable, impermeable, particularly of water

adjective. immune to damage or effect

adjective. not admitting of passage or capable of being affected

"Modest increases in impervious surface due to construction of cottages can in most cases easily be offset by modest removal of impervious surfaces on affected lots, and/or disconnection of downspouts from pipes that discharge runoff to streets."

acid-fast  colorfast  corrosion-resistant  fast  greaseproof  

imperviously  imperviousness  

defenseless  impenetrable  impermeable  impregnable  inaccessible  

Philistine  airtight  ballproof  beyond reach  bombproof