Lest
Unless and lest are semantically related In some cases you can use "Unless" instead a conjunction "Lest".
Unless
Lest and unless are semantically related in except that topic. You can use "Lest" instead a conjunction "Unless".
Mutual synonyms
Both words in one sentence
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For the same reason that many actors do not drink unless they spit, or smoke unless they don't inhale, they can't eat too much fatty food lest it interfere with their acting abilities.
Source: Food Porn - Even Evil Has Standards: The Never students are informed in school that they should not kill unless it is absolutely necessary, lest one cease to be a proper villain and instead become a common thug.
- Gratuitous Japanese: It's generally not a good idea to use random bits of Japanese unless you're a fluent speaker, lest you come across as pandering to Occidental Otaku.
Source: Bad Writing Index
Cite this Source
Unless and Lest. (2016). Retrieved 2026, August 02, from https://thesaurus.plus/related/lest/unless
Lest & Unless. N.p., 2016. Web. 02 Aug. 2026. <https://thesaurus.plus/related/lest/unless>.
Unless or Lest. 2016. Accessed August 02, 2026. https://thesaurus.plus/related/lest/unless.
Google Ngram Viewer shows how "lest" and "unless" have occurred on timeline