39 entries under impervious topic. ×

15
hermetic(verb, adjective, tight, proof, closed)
10
sealed(adjective, tight, proof, hermetic)
9
tight(adjective, proof, hermetic, sealed)
9
watertight(adjective, tight, proof, hermetic)
8
air-tight(adjective, tight, proof, hermetic)
7
impermeable(adjective, tight, proof, impenetrable)
7
waterproof(adjective, water, tight, proof)
5
gas-tight(adjective, tight, proof, hermetic)
4
airproof(adjective, tight, proof, hermetic)
4
hermetical(adjective, tight, proof, hermetic)
3
dampproof(adjective, tight, proof, hermetic)
3
gastight(adjective, tight, proof, hermetic)
3
pressure-tight(adjective, tight, proof, hermetic)
3
proof(adjective, tight, hermetic)
2
enclosed(adjective, tight, proof, hermetic)
2
pressurized(adjective, tight, proof, hermetic)
2
rainproof(adjective, resistant, watertight, waterproof)
2
tightly sealed(expression, adjective, idiom, tight, proof)
1
air-locked(adjective, tight, proof, hermetic)
1
air-proof(adjective, tight, proof, hermetic)
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APASmart Define. (2015). airtight thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/airtight/thesaurus/synonyms
ChicagoSmart Define. 2015. "airtight thesaurus" https://smartdefine.org/airtight/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2015, airtight thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/airtight/thesaurus/synonyms>.
MLASmart Define. "airtight thesaurus" 14 April 2015. Web. 27 September 2026. <https://smartdefine.org/airtight/thesaurus/synonyms>