The Uuijeong was variously referred to as Usang, Ujeongseung, Ugyu, Uhap, or Udae.
[1] Uuijeong was the lowest of the three prime ministers, ranked senior first (jeong-il-pum, Hangul: 정1품, Hanja: 正一品), roughly equal to the Second Deputy Prime Minister in modern day.
[2] The position was created in 1400 by Taejong, replacing the former position Munha Usijung (문하우시중, 門下右侍中) during Goryeo period.
Its name was changed to Uuijeongbusa (우의정부사, 右議政府事) in 1418, then to Uijeongbu Uuijeong (의정부우의정, 議政府右議政) in 1455.
During the Joseon dynasty, Uuijeong was also granted posthumously as an honorable position to fathers-in-law of Grand Internal Princes (대원군, 大院君), Grand Princes (대군, 大君), or Crown Princes' sons (세손, 世孫).