slang A large and/or bulging stomach (as one might experience due to the frequent consumption of beer). If you don't get that beer belly under control, you'll be asked to play Santa Claus this year!
beer belly
and beer gut
n. a large belly. You’re going to end up with a real beer belly hanging over your belt if you don’t let up on that stuff. How long does it take to grow a beer gut like that?