Tummy is an informal, friendly word for your stomach or belly. When your little sister complains about a tummy ache, she means her stomach hurts. When someone says they have butterflies in their tummy before a big presentation, they're describing that nervous, fluttery feeling in their belly.

The word is especially common with young children because it sounds gentle and comforting. A parent might rub a baby's tummy or ask, “Does your tummy feel better now?” after a child has been sick. Adults use it too, though usually in casual or affectionate situations: you might say you're getting a tummy ache from eating too much pizza, or that you laughed so hard your tummy hurt.

While stomach is the more formal, scientific term for the organ that digests food, tummy refers to the whole belly area in a softer, more personal way. You wouldn't use it in a doctor's report or a science essay, but it's perfect for everyday conversation when you want to sound warm and approachable.