The characters combine to mean “old, respected man,” but the term's meaning has become exclusively fixed to “wife's father.” The “老” prefix makes the term more colloquial and common in daily speech compared to the more traditional “丈人”.
In Chinese culture, family relationships are specific and clearly defined. The term 老丈人 reflects this precision. Unlike the generic English term “father-in-law,” which can refer to either spouse's father, 老丈人 *only* refers to the wife's father. The husband's father is called 公公 (gōnggong). This distinction is important. The relationship between a son-in-law (女婿, nǚxu) and his 老丈人 is a key dynamic in the family structure. The son-in-law is traditionally expected to show immense respect and a degree of filial piety towards his wife's parents. He is often seen as a “half-son” (半个儿子, bàn ge érzi) and plays a crucial role in caring for them, especially if they do not have sons of their own. A common cultural practice is for the son-in-law to bring gifts, particularly good quality liquor (like Baijiu) or cigarettes, when visiting his 老丈人. This act is a sign of respect and helps to maintain a harmonious relationship, which is a cornerstone of Chinese social values. The relationship is often a source of pride, jokes, and drama in Chinese media, highlighting its social importance.
老丈人 is primarily a term of reference, not a term of address. You use it when talking *about* your wife's father, not (usually) when talking *to* him.