'Rǔ yá' literally means 'milk teeth'—'rǔ' (乳) means 'milk' or 'breast', evoking the early life stage when these teeth emerge, and 'yá' (牙) means 'tooth'. Together, they refer to the first set of teeth that children develop, typically appearing between 6 months and 3 years of age and gradually being replaced by permanent teeth from around age 6 onward.

This term is standard in medical, dental, and everyday contexts in Chinese. Unlike the more technical term 'deciduous teeth', 'rǔ yá' is widely used by parents, pediatricians, and educators. It emphasizes the temporary, developmental nature of these teeth—just as milk nourishes infants, these teeth serve a foundational but transitional role in chewing, speech development, and guiding permanent tooth alignment.