Adjective: imperviable
- Not admitting of passage or capable of being affected
"The waterproof coating made the fabric imperviable to moisture";
- impervious
See also: acid-fast, colorfast [US], colourfast [Brit, Cdn], corrosion-resistant, fast, greaseproof, impermeable, ladder-proof [Brit], mothproof, moth-resistant, proof, resistant, rot-resistant, runproof, run-resistant, soundproof
Antonym: pervious