What does the word lest mean?

Usage examples for lest

  1. I have written a good deal, but I dare not read it over, lest it should be nothing worth. – The Lilac Sunbonnet by S.R. Crockett
  2. " You who weep too late, take care lest you weep more than one day. – Child of a Century, v3 by Alfred de Musset
  3. Lupin was afraid lest the other should turn back and take to flight. – The Crystal Stopper by Maurice LeBlanc