When you sigh, you let out a deep breath, as a way of expressing feelings such as disappointment, tiredness, or pleasure.

If you sigh something, you say it with a sigh.

If the wind sighs through a place, it moves through the place with a sound like a sigh.

If people breathe or heave a sigh of relief, they feel happy that something unpleasant has not happened or is no longer happening.