'Xiǎo bà' is a colloquial, regionally used term—most common in parts of southern China and among younger speakers—to refer to a young father, typically one who became a dad in his teens or early twenties. Literally, 小 (xiǎo) means 'small' or 'young', and 爸 (bà) means 'dad'; together, they emphasize youthfulness rather than biological relationship. It may also be used affectionately or teasingly for a stepfather who is significantly younger than the child’s mother—or even for an older male caregiver who isn’t biologically related but fills a paternal role.

The term carries informal, sometimes playful or slightly ironic connotations; it's rarely used in formal writing or official contexts. Unlike standard terms like 父亲 (fùqīn) or 爸爸 (bàba), 小爸 reflects contemporary speech patterns where age, appearance, or social role influence kinship labels. It's not interchangeable with 'stepdad' in all cases—context and speaker intention matter greatly.