Definition of lest:
(conjunction) :
for fear that; that . . . not; in order that . . . not; in case; that (without the negative particle); -- after certain expressions denoting fear or apprehension
"he won't go outside, lest he be eaten by those ravenous eagles"
Definition of lest:
(conjunction) :
for fear that; that . . . not; in order that . . . not; in case; that (without the negative particle); -- after certain expressions denoting fear or apprehension
"he won't go outside, lest he be eaten by those ravenous eagles"