Koshu (title) (公主)

Koshu (公主) indicates the daughters of the Chinese Emperors. This was also used a title for them. In ancient times, those daughters were called with the names of the lands conferred on them as they married, in a form of the place name and 'Koshu' (e.g. Taihei Koshu, Anraku Koshu), but this cannot be applied to the names in the Ming and Qing periods because the title became treated as a title indicating nobility.

In ancient times, the eldest daughters of emperors were called as Genkoshu (e.g., the eldest daughter of Liu Pang was called "Lu (or Lo in Japanese) Genkoshu," 魯元公主, or the Genkoshu given the land in Lu). From the Tang and Song Dynasties onwards, sisters of the reigning emperor were given the title of Chokoshu (roughly, elder Koshu), and aunts and Koshu ladies in the previous reigns were given the title of Daichokoshu (roughly, great elder koshu, e.g., 秦魯国賢穆明懿大長公主), to distinguish from daughters of the reigning emperor, with better treatment than the daughters. In the Qing Dynasty, the title of Koshu were distinguished into two: daughters of empresses were called as 固倫公主; and daughters of other imperial consorts as和碩公主.

In the Northern Sung dynasty, the title Koshu was abolished for a short time and the title Teiki (帝姫) was used instead (e.g., 嘉徳帝姫.)
It is said that the title Teiki was in the style of the Shou dynasty.

When a subject of an emperor married a Koshu (any husband to a Koshu had to come from a different family, thus a non-sovereign family, as in China and Korea marriage within the family, thus with the same surname, has long been a taboo), it was called尚公主, and the husband was given a title of駙馬都尉 (during the Qing Dynasty, it was 額駙).

In Korea, Koshu was pronounced as Konju, and indicated a daughter of a king and queen, while a daughter from other king consort was given a title of Okishu or 翁主. Accordingly, the title Kosh was given to daughters of the emperor and empress in the Great Korean Empire (1887-1910).

In the present People's Republic of China and the Republic of Korea, Koshu has almost the same meaning as 'O-himesama' in Japanese, meaning a princess, without any legitimate claim to it.

Origin of the title

The origin of this word 'Koshu' is explained by the fact that marriages of daughters of the monarch were presided (公) by three Ministers (each called as 公 or 侯).