A cummerbund is a fancy piece of clothing that adults wear to make themselves look really spiffy at special events, like weddings or fancy dinners. It's kind of like a big, wide belt that goes around your belly. It's usually made of shiny fabric, like satin or silk, and it usually matches your bow tie. The cummerbund helps hold your shirt down and makes you look more elegant. Plus, it's a fun word to say!