“Lest” is a formal conjunction that means “for fear that” or “in order to prevent something from happening.”

Basic meaning

  • “Lest” introduces something negative that you want to avoid or prevent.
  • It is mainly used in formal or literary English today, not in everyday casual speech.

Common patterns

  • “Lest” + clause with a verb:
    • “She spoke quietly lest anyone hear her.”
  • Often used after verbs about fear or worry:
    • “He was afraid lest he say too much.”

Example sentences

  • “He gripped his brother’s arm lest he be trampled by the mob.”
  • “Lest anyone should doubt my story, I have brought documents to prove it.”
  • “And lest you think I’m joking, everything I’ve said is true.”

Quick nuance

  • Core idea: preventing or fearing a bad outcome.
  • Today, people more often say “in case,” “so that … not,” or “because I don’t want…” instead of “lest” in normal conversation.

If you share a sentence you’re unsure about, it can be rewritten with or without “lest” to show the difference.