lest
Americanconjunction
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for fear that; so that (one) should not (used negatively to introduce a clause expressive of an action or occurrence requiring caution).
He kept his notes by his side lest faulty memory lead him astray.
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that (used after words expressing fear, danger, etc.).
There was danger lest the plan become known.
idioms
conjunction
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so as to prevent any possibility that
he fled the country lest he be captured and imprisoned
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(after verbs or phrases expressing fear, worry, anxiety, etc) for fear that; in case
he was alarmed lest she should find out
Etymology
Origin of lest
First recorded before 1000; Middle English leste, contraction of the lesse the, thi les the; late Old English the lǣste, earlier thȳ lǣs the, literally, “whereby less that” ( thȳ instrumental case of the demonstrative and relative pronoun, lǣs less, the conjunction)
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Some members of her party have pushed Sheinbaum to sever ties with Rocha Moya and other leaders suspected of links to organized crime, lest Morena be tainted by the allegations.
From Los Angeles Times • Jun. 3, 2026
There are many examples of match officials being placed in harmful situations but with individuals fearful of speaking out lest it exacerbates the situation or causes further alarm to friends, family and colleagues.
From BBC • May 15, 2026
Others note that payments involve all sorts of security and encryption issues, lest someone’s financial information become exposed on an AI platform.
From MarketWatch • Apr. 25, 2026
When the tech industry executive met with his son’s guidance counselor, the school confirmed that it rarely withheld diplomas from chronically absent pupils, lest these students suffer later in life.
From The Wall Street Journal • Apr. 3, 2026
He tried to sight down along the muzzle, tried to remember to aim low, but was afraid to point down lest he lose the ball again.
From "The Fighting Ground" by Avi
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
