This is the 10288th most frequent Russian word.
боялись
"Боялись" means "were afraid."
The word 'боялись' is used here to describe an emotional response (fear) towards a natural phenomenon.
Мы боялись грома и молний.
We were afraid of thunder and lightning.
In this sentence, 'боялись' indicates reluctance or hesitation due to fear regarding communication of the truth.
Они боялись говорить правду.
They were afraid to tell the truth.
Here, 'боялись' illustrates a fear or aversion towards a specific activity (swimming in deep water).