Humidity
Humidity explained in an easy to understand way:
Imagine trying to fit all your clothes into a suitcase that seems just a little too small. Just like the suitcase has a limit to how many clothes it can hold, the air has a limit to how much water vapor it can contain. Humidity is like the fullness of that suitcase—the more water vapor in the air, the closer it is to being 'full,' just as a suitcase gets heavier and harder to close as you pack more clothes into it.
Practice Version
Humidity: The amount of water vapor in the air. Humidity. Humidity is how much water is in the air around us.