lest

[ lest ]
/ lɛst /

conjunction

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.
that (used after words expressing fear, danger, etc.): There was danger lest the plan become known.

Origin of lest

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 relative particle)
Can be confusedleast lest let's
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for lest

British Dictionary definitions for lest

lest

/ (lɛst) /

conjunction (subordinating; takes should or a subjunctive verb)

so as to prevent any possibility thathe fled the country lest he be captured and imprisoned
(after verbs or phrases expressing fear, worry, anxiety, etc) for fear that; in casehe was alarmed lest she should find out

Word Origin for lest

Old English the lǣste, earlier thӯ lǣs the, literally: whereby less that
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for lest

lest


conj.

c.1200, contracted from Middle English phrase les te "less that," from Old English phrase þy læs þe "whereby less that," from þy, instrumental case of demonstrative article þæt "that" + læs (see less) + þe "the." The þy was dropped and the remaining two words contracted into leste.

Online Etymology Dictionary, © 2010 Douglas Harper