Fizzy describes a liquid filled with tiny bubbles that tickle your tongue and make a soft hissing sound. Soda is fizzy. So is sparkling water, champagne, and the foam on root beer floats. When you pour a fizzy drink, you can see thousands of little bubbles racing to the surface and popping.

The bubbles in fizzy drinks come from carbon dioxide gas dissolved in the liquid under pressure. When you open the bottle or can, the pressure releases and the gas escapes as bubbles. That's why a fresh soda is fizzier than one that's been sitting open for an hour: the carbon dioxide gradually escapes into the air.

The word captures both the feeling and the sound. Fizzy drinks create that pleasant tingling sensation on your tongue, and if you listen closely, you can hear them fizzing. Scientists use effervescent to describe the same thing, but fizzy is simpler and more fun to say. When something loses its bubbles, we say it's gone flat, the opposite of fizzy.