Ranked by relevance and common usage.
Keep "fastness" 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 "fastness" 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 "fastness", 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 "fastness" or choose a simpler alternative from the closest-match group.
OpenGloss and ConceptNet supply richer edges like generalizations, collocations, and derivations.
5 translations across 2 languages.
15 total sentences available.
[T]he thing, as it is, having firſt taken vp her ſtand in the memory, and there by the way of knowledge and witting, imprinted it-ſelfe, it were hard it ſhould not repreſent it ſelfe to the imagination, diſplacing and ſupplanting falſehood, which therein can have no ſuch footing, or ſetled faſtneſſe: […]
Source: wiktionary
[T]his is the ſure, infallible Teſt of Love, that the Meaſure of its Strength is to be taken by the Faſtneſs of its Hold.
Source: wiktionary
[Frog:] Why are all of us fleein'? What dire peril threatens our sylvan fastness? [Bug:] Just run! Your fastness shouldn't be too slow.
Source: wiktionary
But now his cruelty ſo ſore ſhe drad, / That to thoſe fennes for faſtneſſe ſhe did fly, / And there her ſelfe did hyde from his hard tyranny.
Source: wiktionary
Showing 4 of 15 available sentences.
Closest matches include swiftness, acropolis, air speed, aplomb, balance.
Compare the replacement against real sentence context. This entry includes sample sentences so you can check tone, grammar, and meaning before swapping words.