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.
Do I want to have to send out a little digital warrior to fight for me every time I want to book a golf tee time, lest there be none left?
From Slate ● Oct. 14, 2026
This is a matinee coffee film, not a popcorn feature, lest anyone expect edge-of-your-seat tension.
From Salon ● Oct. 11, 2026
In Borneo's West Kalimantan province, at lest 15 of the animals have been rescued from flames and haze since July, some stuck in plantations after fires cut off access to their forest home.
From Barron's ● Sep. 11, 2026
Teams are always circumspect about doing anything too exotic during the preseason, lest they give regular-season opponents something to study.
From Los Angeles Times ● Aug. 14, 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
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Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.