The phrase "brought to one's knees" typically refers to someone who has been completely overwhelmed or defeated by a situation. However, there are several synonyms for this expression that can be used to convey a similar meaning. One such synonym is "crushed," which suggests that someone has been emotionally or physically destroyed by an experience. Another option is "overpowered," which implies that someone has been overcome by a force that is more powerful than they are. Other synonyms include "subdued," "defeated," "helpless," and "powerless." Using any of these words can help to convey the same sense of defeat and vulnerability as the original phrase.
