Glug is the deep, hollow sound that liquid makes when it pours out of a narrow opening, like when you tip a water jug and hear that glug-glug-glug as the water rushes out. The sound happens because air bubbles need to push back into the container as the liquid flows out, creating that distinctive gurgling rhythm.

You hear glugging when pouring juice from a bottle, draining the last bit of milk from a carton, or watching bathwater spiral down the drain. The narrower the opening, the louder and slower the glugs, because the air and liquid have to take turns squeezing through.

People use glug as a verb too: “She glugged a glass of water after soccer practice.” It suggests drinking in big, thirsty gulps rather than taking small, polite sips. Writers love this word because it's onomatopoeia, meaning the word sounds like what it describes. When you read “glug,” you can almost hear the sound in your mind.