As an expert in grammar and language usage, I can tell you that the conjunction ‘LEST’ is primarily used to introduce an idea or clause that expresses a fear or caution about what might happen if a certain action is taken.
The word ‘LEST’ is an old English contraction of the phrase “for fear that.” This conjunction is typically used in a negative clause, and can be interchanged with the phrase “in case.”
Here is an example: “The hikers carried bear spray with them LEST they encounter a grizzly bear.” In this sentence, ‘LEST’ is used to express the caution that the hikers took in carrying bear spray, which they believed might be necessary if they were to encounter a dangerous animal.
Another example would be, “I double-checked the address LEST I end up at the wrong location.” In this sentence, ‘LEST’ is used to indicate the fear or caution that the speaker has about getting lost, and emphasizes the importance of double-checking to prevent this from happening.
In summary, ‘LEST’ is a cautionary conjunction that expresses a fear or caution about what might happen if a certain action is taken. It should be used in negative clauses, and can be interchanged with the phrase “in case.”