This section does not cite any sources
. (November 2013)
The zì, sometimes called the biǎozì（表字）or "courtesy name", is a name traditionally given to Chinese males at the age of 20, marking their coming of age. It was sometimes given to females upon marriage. The practice is no longer common in modern Chinese society. According to the Book of Rites, after a man reaches adulthood, it is disrespectful for others of the same generation to address him by his given name, or míng. Thus, the given name was reserved for oneself and one's elders, while the zì would be used by adults of the same generation to refer to one another on formal occasions or in writing; hence the term "courtesy name".
The zì is mostly disyllabic, consisting of two Chinese characters, and is usually based on the meaning of the míng or given name. Yan Zhitui of the Northern Qi dynasty believed that while the purpose of the míng was to distinguish one person from another, he asserted that the zì should express the bearer's moral integrity.
The relation which often exists between a person's zì and míng may be seen in the case of Chiang Kai-shek (蔣介石), whose ming was Zhōngzhèng (中正，Romanized as Chung-cheng) and zi was Jieshi (介石，Romanized as Kai-shek). Thus he was also called 蔣中正 (Chiang Chung-cheng) in some contexts.
Another way to form a zì is to use the homophonic character zǐ (子) – a respectful title for a male – as the first character of the disyllabic zì. Thus, for example, Gongsun Qiao's zì was Zǐchǎn (子產), and Du Fu's: Zǐměi (子美).
It is also common to construct a zì by using as the first character one which expresses the bearer's birth order among male siblings in his family. Thus Confucius, whose name was Kǒng Qiū (孔丘), was given the zì Zhòngní (仲尼), where the first character zhòng indicates that he was the second son born into his family. The characters commonly used are bó (伯) for the first, zhòng (仲) for the second, shū (叔) for the third, and jì (季) typically for the youngest, if the family consists of more than three sons. General Sun Jian's four sons, for instance, were Sun Ce (伯符, Bófú), Sun Quan (仲謀, Zhòngmóu), Sun Yi (叔弼, Shūbì) and Sun Kuang (季佐, Jìzuǒ).
The use of zì began during the Shang dynasty, and slowly developed into a system which became most widespread during the succeeding Zhou dynasty. During this period, women were also given zì. The zì given to a woman was generally composed of a character indicating her birth order among female siblings and her surname. For example, Mèng Jiāng (孟姜) was the eldest daughter in the Jiāng family.
Prior to the twentieth century, sinicized Koreans, Vietnamese, and Japanese were also referred to by their zì. The practice was also adopted by some Mongols and Manchus after the Qing conquest of China.