Tummy/ˈtʌmi/ Definition 1 of 2Pro Tip 1/3Informal Use Tummy is often used in informal situations, such as talking with friends or with children. My little sister said her tummy hurts after eating candy. Pro Tip 2/3Child-Friendly Term Tummy is a less formal word used by or with children instead of 'stomach'. Mom, my tummy feels weird – can I stay home from school? Pro Tip 3/3Physical Sensation Refers to physical feelings related to hunger, fullness, or minor pains. I can't eat another bite; my tummy is stuffed!