lest

conjunction

ˈlest 

: for fear that

—often used after an expression denoting fear or apprehension

worried lest she should be late

hesitant to speak out lest he be fired

Word History

Etymology

Middle English les the, leste, from Old English thȳ lǣs the, from thȳ (instrumental of thæt that) + lǣs + the, relative particle

First Known Use

before the 12th century, in the meaning defined above

Kids Definition

lest

conjunction

(ˌ)lest 

: for fear that

tied the dog lest it should escape