conj
lest
lehst
conj
1
Used to introduce something that must be avoided or guarded against; so that not; in case.
"She kept quiet lest she reveal the surprise."
"Take an umbrella, lest it rain later."
How to Use Lest
Learner’s notesIn plain EnglishA formal way of saying "so that (something bad) doesn't happen" or "in case."
When to use it
Fairly formal or literary; in everyday speech people usually say "in case" or "so that ... doesn't" instead.
Common pairings
lest we forget
lest it happen again
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She kept quiet _____ she reveal the surprise.
Etymology
A contraction of Old English forms meaning roughly "whereby less that" — literally "so that it be less the case that."