tummy

This term carries a soft, affectionate, or juvenile connotation, making it the standard choice when speaking to children or referring to infants. It evokes a sense of warmth and vulnerability, contrasting with the clinical precision of stomach or the anatomical specificity of abdomen.

While it refers to the same physical area as stomach, it is rarely used in medical contexts or formal reports. Using this word in a professional setting would be perceived as overly casual or inappropriately childish.