Ranked by relevance and common usage.
Keep "filthiest" 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 "filthiest" 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 "filthiest", 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 "filthiest" 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.
Tunnels often feature in fictional journeys, so I will end with quotations from a fairly recent novel, Howard Spring's "Fame is the Spur", published in 1940, in which there is a journey from Manchester to Bradford via the Calder Valley route: "Ay, we're going through Todmorden. We'll soon be in t' tunnel, and when we get to t' other end we'll be in Yorkshire," and "Ah think this is t' filthiest tunnel in t' world."
Source: wiktionary
Otherwise, overseas coking coal will be moved to the UK by bulk ocean carrier, which are among the filthiest polluting objects on the face of the Earth we seek to protect.
Source: wiktionary
Closest matches include atrocious, dirtiest, grimiest, obscene, uncleanest.
Compare the replacement against real sentence context. This entry includes sample sentences so you can check tone, grammar, and meaning before swapping words.