An eyebrow is the curved strip of hair that grows above each of your eyes. Your eyebrows have an important job: they catch sweat and rain before it can drip into your eyes, acting like little awnings on your face.

But eyebrows do something even more interesting. They're one of the most expressive parts of your face. When you raise your eyebrows, you might be showing surprise or asking a question. When you furrow them (pull them together), you might be confused, concentrating hard, or frustrated. A single raised eyebrow can express doubt or suspicion without saying a word. People read eyebrows almost as much as they read eyes when trying to understand what someone is feeling.

The expression raise eyebrows means to surprise people or make them question whether something is appropriate. If you showed up to school wearing pajamas, that would definitely raise some eyebrows among your classmates and teachers. Similarly, eyebrow-raising describes something surprising or questionable: “His decision to bring a pet snake to the library was eyebrow-raising.”