To barf means to vomit or throw up. When you barf, the food in your stomach comes back up through your mouth, usually because you're sick, you've eaten something bad, or you're feeling nauseated.

It's a casual, somewhat humorous word that kids often use instead of more formal words like “vomit” or “throw up.” You might hear someone say “I feel like I'm going to barf” when they have a stomachache or ate too much candy. The word captures that sudden, unpleasant experience without sounding too medical or serious.

People also use barf to express strong disgust with something, even when they don't literally mean they'll throw up. A kid might say “That moldy sandwich makes me want to barf” or “The smell of those gym socks is totally barf-inducing.”