The conjunction lest means (1) for fear that, or (2) in order to avoid. It is followed by something the speaker thinks should be avoided. For example, we might write, “We’re going to proofread this twice lest we make errors that hurt our credibility.”
The clause introduced by lest is usually in the subjunctive mood, but this is not required for writers who aren’t comfortable with subjunctive constructions.
Examples
I won’t waste your time responding point-by-point lest I give credence to unsubstantiated allegations and tortured innuendo. [Dallas News]
Now, lest I appear ungrateful for the relative privilege I personally enjoy in the world, let me be quick to acknowledge that fact here. [Why I Hate Abercrombie and Fitch, Dwight A. McBride]
I suppose it is unwise of me to make this confession now, lest our insurance company reads this article. [Daily Mail]
Don’t push people too hard, lest you damage close friendships unnecessarily. [Numerology, Hans Decoz]
Lest people did not get the point, he went on to say they ”are the vilest form of human life” and should ”rot in hell”. [Sydney Morning Herald]