Why did Su Shi call his sister Niang?

In the Song Dynasty, "Niang" was not a respectful name for older women, but a nickname for girls of the same generation or younger generation. People in the Tang Dynasty also had this habit. Do you remember Du Fu's long poem about Gong Sundaniang's sword dancing? The so-called "Gong Sundaniang" is not an old lady named Sun, but a little girl named Sun, but the little girl is the eldest in the family.

In addition to a younger sister, Su Shi also has a sister whose name is Su Ba Niang instead of Su Xiaomei. Su Shi once wrote a letter to his younger brother Su Zhe, saying that Ba Niang was very kind to our two brothers in those years, referring to his sister.

Seeing this, a clever friend must have asked a question: since she is my sister, Su Dongpo should call her "Eight Sisters". How can she be called "Eight Mothers"? Because the meaning of the name "Niang" in the Song Dynasty is different from today, modern people call it Niang, which refers to the mother; People in Song Dynasty called Niang, which may refer to sisters or daughters. If you don't believe me, take a look at the following hard evidence:

Su Zhe has a daughter, and he calls her "Wan Niang". Huang Tingjian also has a daughter. He called her "thirty-three niang". Yue Fei has a daughter. Before Yue Fei was killed, she sent someone to meet her family in Jiujiang, Jiangxi Province, and specially told her: "My mother is still young and it is difficult to get hot during the trip, so she can cut interest rates." This means that the weather is very hot, so we should have more rest on the road. My daughter is still young, so don't let her get sick.