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.
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
This is the Court’s classic requirement for the judiciary to hear cases, lest courts be asked to decide all manner of differences of opinion.
From The Wall Street Journal ● Sep. 1, 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
Notwithstanding the hazard was too great for us to take refuge in that mansion, lest some agent of the College return, I wished to see it now that my circumstances were so deeply changed.
From "The Astonishing Life of Octavian Nothing, Traitor to the Nation, Volume II: The Kingdom on the Waves" by M.T. Anderson
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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.