Pronunciation: (lest), [key]
1. 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.
2. that (used after words expressing fear, danger, etc.): There was danger lest the plan become known.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.