I. ˈlest conjunction
Etymology: Middle English lest the, leste, lest, from Old English thȳ lǣs the, from thȳ (instrumental of thæt this, that, which) + lǣs, adjective, less + the, relative particle — more at that , less
1. : for fear that : so that (one) should not
prefer a man who acts decisively … rather than one who hesitates lest he be guilty of imprudence — C.B.Kelland
2. : that — used after an expression denoting fear to introduce the cause of apprehension
live in daily apprehension lest the wholesome sons and daughters whom they commit to a college return to them as brazen fools — W.L.Sullivan
II.
archaic
variant of least