What is another word for "impervious"?

Roget's Thesaurus (1911) lists these synonyms for "impervious": air, alley, bar, blind, block, blockade, bolt, bung, button, caecal, caecum, choke, clinch, close, closure, cloud, cloudiness, cloudy, constipation, contraction, cork, corner, cram, cul-de-sac, dam, dim, dirty, door, down, embolus, fill, film, fog, foggy, fuliginous, fumid, haze, haziness, hazy, hermetically.