10
waterproof(adjective, water, tight, proof, impervious)
9
tight(adjective, proof, impervious, hermetic, sealed)
9
hermetic(adjective, tight, proof, impervious, airtight)
8
impermeable(adjective, tight, proof, impervious, impenetrable)
7
airtight(adjective, tight, proof, impervious, hermetic)
7
impervious(adjective, fast, short, unyielding, unbending)
7
sealed(adjective, tight, proof, impervious, hermetic)
7
unassailable
6
rainproof(adjective, resistant, impervious, waterproof)
6
unshakable
5
bulletproof
4
firm(noun, adjective)
4
leakproof
4
resistant(adjective, unaffected, unyielding, unbending, impervious)
4
snug
4
weatherproof
3
dampproof(adjective, tight, proof, impervious, hermetic)
3
fast
3
gastight(adjective, tight, proof, impervious, hermetic)
3
hermetical(adjective, tight, proof, impervious, hermetic)
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APASmart Define. (2015). watertight thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/watertight/thesaurus/synonyms
ChicagoSmart Define. 2015. "watertight thesaurus" https://smartdefine.org/watertight/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2015, watertight thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/watertight/thesaurus/synonyms>.
MLASmart Define. "watertight thesaurus" 13 April 2015. Web. 21 September 2026. <https://smartdefine.org/watertight/thesaurus/synonyms>