Which word describes a state of confusion or bewilderment?

The term that describes a state of confusion or bewilderment is "nonplused." This word indicates a situation where someone is perplexed or at a loss for words, often due to being confronted with something unexpected or challenging to understand. When a person feels nonplused, they experience an overwhelming sense of confusion that can leave them unsure of how to proceed or what to say.

In contrast, "clear-headed," "sure," and "lucid" all connote a sense of clarity and understanding. These words suggest being mentally sharp, decisive, or able to think effectively, which are the opposite of confusion. Thus, "nonplused" is the appropriate choice for conveying a state of bewilderment.