Correct usage of "lest"
Which of the followings is/are the correct usage of the word "lest"? How are these different from each other?
- ...hesitant to speak out lest he be fired.
- ...hesitant to speak out lest he'd be fired.
- ...hesitant to speak out lest he would/will be fired.
P.S. I took point number 1 as the reference for this question from the definition of lest from the Merriam-Webster Dictionary.
Sentence 1 would be most common, although they all are OK. There is no significant difference in meaning between them. 2 and 3 are somewhat awkward,
"Lest" is not used so much these days. People tend to find other ways of expressing the idea.
"Lest" as a conjunction may have entered English as a translation of a Norman French phrase (modern French à moins que, similar to Spanish a menos que). Both the French and Spanish generally mean "unless". But "lest" may come from an Anglo-Saxon term of identical construction with the French and Spanish.
Sometimes "lest" has similar meaning to "unless", but is uncommon
Lest we stay here until 5, we might be fired.
Unless we stay here until 5, we might be fired.
I hope this helps.