Ranked by relevance and common usage.
Keep "air-tight" when the sentence already sounds natural, when a synonym would add unintended emphasis, or when readers need the most familiar wording. A synonym should clarify or sharpen the message, not simply make the sentence look more varied.
If two options seem close, choose the one that best matches the audience and purpose of the sentence.
Choose a synonym only if it keeps the core idea of "air-tight" intact in the sentence you are editing.
Check whether the replacement sounds more formal, casual, emotional, technical, or forceful than the original word.
Read the full sentence after the swap. Keep the synonym only when the sentence becomes clearer or more precise.
Review note: Synonym lists are ranked with lexical data and reviewed for practical writing value. Use the comparison notes, sentence evidence, and source labels together; a high-ranking synonym can still be wrong when the audience, register, or grammar changes.
After choosing a replacement for "air-tight", read the sentence once for meaning and once for rhythm. The best synonym should feel natural in the full sentence, not only accurate in a word list.
If the synonym makes the sentence slower, vaguer, or more dramatic than intended, keep "air-tight" or choose a simpler alternative from the closest-match group.
OpenGloss and ConceptNet supply richer edges like generalizations, collocations, and derivations.
2 total sentences available.
Further along the gallery was the huge skeleton barrel of a brontosaurus. My museum hypothesis was confirmed. Going toward the side of the gallery I found what appeared to be sloping shelves, and clearing away the thick dust, I found the old familiar glass cases of our own time. But these must have been air-tight to judge from the fair preservation of some of their contents.
Source: wiktionary
Spacecraft compartments can be isolated by air-tight doors in case of decompression. The cinematic version of explosive decompression is fiction; holed compartments either take enough damage that the occupants are killed instantly, or leak slowly enough that they are able to reach protective gear.
Source: wiktionary
Closest matches include airtight, gas-tight.
Compare the replacement against real sentence context. This entry includes sample sentences so you can check tone, grammar, and meaning before swapping words.