‘乳名’ (rǔ míng) literally combines ‘乳’ (rǔ), meaning ‘milk’ or ‘breast’, and ‘名’ (míng), meaning ‘name’. Historically, it refers to the name given to a child shortly after birth—often before formal naming ceremonies—and was traditionally used during early nursing years, hence the character ‘乳’. Today, it functions as a warm, affectionate childhood nickname used by family members and close relatives, distinct from one’s formal given name (本名 běn míng) or official name (正式名字 zhèngshì míngzi).

This term carries strong familial and cultural connotations; it reflects intimacy, care, and informal social bonds. While commonly used for young children, some adults continue to be called their 乳名 by parents or grandparents throughout life. It is rarely used in formal settings, schools, or official documents, and is not equivalent to general nicknames (绰号 chuòhào), which may carry teasing or humorous overtones.