[2] In ancient usage, the characters of meng (孟), zhong (仲), shu (叔) and ji (季) were used to denote the first, second, third and fourth eldest sons in a family.

[3] According to analysis based on the early 11th-century dictionary Guangyun, in Middle Chinese the character was pronounced [kwi].

[3] The main origin of the Ji 季 surname is the state of Lu during the Spring and Autumn period of ancient China.

[3][5] Several other states of the Zhou dynasty, such as Qi and Wei, also had noble lineages that adopted Ji 季 as their surname.

[3] During the Ming and Qing dynasties, several Mongol and Manchu clans adopted the Ji surname, and many Ji-surnamed people in Northeast China are from this origin.