Nyobona was a name that a nyobo (a court lady) called herself in attendance. Her master or colleagues called her by her nyobona instead of her real name. Moreover, the formality of the name itself is called nyobona.
From the Heian period to the Kamakura period, women's names were rarely listed in genealogy, etc. Therefore, their real names were hardly known no matter how popular they were.
Nyobona is usually created from the title or rank of the household head, such as her father, brother, or husband. For example, Shikibu in Murasaki Shikibu was from her father FUJIWARA no Tametoki's title Shikibu taijo (Senior Secretary of the Ministry of Ceremonial), and Shonagon in Sei Shonagon was from shonagon (lesser counselor) (it is said that her brother became shonagon). Moreover, poet Ise's father was the governor of Ise Province, and poet Sagami's husband was the governor of Sagami Province. However, a word that indicates her trait might be added in order to distinguish from others who has same name. Sei (清) in Sei Shonagon indicated she was from the Kiyohara (清原) clan, and Murasaki (紫) in Murasaki Shikibu came from Murasaki no ue (紫の上), a character of her novel "Tale of Genji," according to one view. Moreover, Izumi Shikibu was made from her husband's title, governor of Izumi Province and her father's title, shikibu taijo. Another example is Daini no Sanmi that was made from a combination of her husband's title, dazai no daini (Senior Assistant Governor-General of the Dazai-fu offices) and her own court rank, jusanmi (junior third court rank). Furthermore, Koshikibu no Naishi was called 'Koshikibu' (small-shikibu) because she and her mother, Izumi Shikibu, served FUJIWARA no Shoshi, the second consort of the Emperor Ichijo, at the same time.
Moreover, in order to avoid being confused with a person of the same name but of a different generation, the master's family name might be prefixed to the original nyobona of a nyobo who shared a name with another family's nyobo or who had made their name as a poet or a novelist. Especially, the custom started in the insei period (period of the government by the Retired Emperor) and became popular. For example, Yushi Naishinno-ke no Kii, Baishi Naishinno-ke no Senji (as known as Rokujosaiin no senji), Taikenmonin Horikawa, Nijoin no Sanuki, Kokamonin no Betto, Inpumonin no Taifu, and 摂政家丹後 (as known as Gishumonin no Tango) were named in that manner.