Meaning:

Literally meaning “peony flowers,” this term is a homophone of the phrase “母单花,” which is short for “母胎单身花” (mǔtāi dānshēn huā). As the character “花” is used as a metaphor for a woman, this term actually refers to a woman who has never been in a relationship, that is, “single since birth.” Compared with another term that compares singles to dogs (单身狗, dānshēngǒu), this is more flattering. So many women are willing to jokingly call themselves “peony flowers.”

Example:

A: 你有男朋友吗？

Nǐ yǒu nánpéngyou ma？

Do you have a boyfriend?

B: 没有，我们宿舍都是牡丹花。

Méiyǒu，wǒmen sùshè dōushì mǔdānhuā。

Nope. None of the girls in my dormitory has been in a relationship before.