There is what appears under normal circumstances to be an uncrossable boundary, a total barrier.
Source: wiktionary
Ranked by relevance and common usage.
Keep "uncrossable" 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 "uncrossable" 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 "uncrossable", 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 "uncrossable" or choose a simpler alternative from the closest-match group.
4 total sentences available.
There is what appears under normal circumstances to be an uncrossable boundary, a total barrier.
Source: wiktionary
And it’s brilliantly stitched together by motifs of chrysalises and movies and by a joyous abundance of metaphor and simile: “the ding of a bicycle bell like struck crystal”; a woman “talking for much of the day in a steady soft uncrossable stream.”
Source: wiktionary
There are very few bridges on the footpaths in Skye and even short periods of heavy rain can cause rivers to rise rapidly, often making them uncrossable.
Source: wiktionary
There are two Underground stations. That serving the District and Piccadilly is on one side of an uncrossable road called Hammersmith Broadway; that serving the Hammersmith & City is on the other side. Whichever exit you emerge from, at whichever station, you are immediately lost.
Source: wiktionary
Closest matches include unpassable.
Compare the replacement against real sentence context. This entry includes sample sentences so you can check tone, grammar, and meaning before swapping words.