To sigh means to let out a long, deep breath that you can hear, usually because you're feeling tired, sad, frustrated, or relieved. When you sigh, air flows out of your lungs in a way that makes a soft sound, almost like a gentle wind.

People sigh for different reasons. You might sigh when you sit down after a long day at school, your body showing how worn out you feel. A student might sigh when looking at a difficult homework assignment, that breath expressing frustration before they dive in. Sometimes a sigh shows disappointment, like when your team loses a close game. But sighs aren't always negative: you might sigh with relief when you finally find your lost jacket, or sigh contentedly while settling into a comfortable chair with a good book.

A sigh can also be a noun: “She let out a sigh of relief when the test was over.”

Interestingly, sighing happens automatically too. Scientists have discovered that people sigh many times an hour without even noticing, which helps keep our lungs working properly by reinflating tiny air sacs. But the sighs we're aware of, the ones we feel, those are our bodies and emotions speaking a language without words.