Long hair, that is, waist, long hair and waist are all adjective phrases, which are used to describe the length of women's hair, meaning that women's hair is so long that it can hang down to the waist or even lower. These two words have the same meaning.

Waist-length hair describes a girl's unswerving love for a boy, which comes from a couple's conversation: "If you accompany me from shoulder-length short hair to waist-length hair, then I will accompany you from innocence to stability." The implication is: Will you marry me and go home when my hair grows to my waist?