What is chonsu? In Korean society, there is something called chonsu which indicates the degree of kinship in family relationships. It is a number representing the degree of distance and closeness between relatives. It is not known exactly when the concept of chonsu began to be used in Korea, but there is a clear record of it in the National Code of the Joseon Dynasty called Gyeongguk Daejeon. According to the records, it seems that chonsu can be traced back at least to the Goryeo Dynasty.
Chon means kinship and su means number. According to chonsu, one’s spouse is 0 degrees or young chon of distance. Parent-child relationship is 1 degree of separation, and sibling relationship is 2 degrees. Based on this, the extension can be infinitely extended.
Parents’ siblings are easy to remember because one’s mother’s brother is literally called samchon or “3 degree kin”. All uncles and aunts have different nomenclature depending on their gender and side of the family but they are all 3 degrees of closeness.
The children of my uncles and aunts, otherwise known as cousins, are 4 degrees, or sachon. This is also easy to remember because the word for cousin in Korean is sachon.
The children of cousins are 5 degrees close or ohchon. And the children of one’s cousins are connected to one’s own children by 6 degrees or yukchon.
Chonsu: Degrees of Family Distance
Spouse: 0 chon (young chon)
Parents: 1 chon (il chon)
Children: 1 chon (il chon)
Grandparents: 2 chon (yi chon)
Siblings: 2 chon (yi chon)
Greatgrandparents: 3 chon (sam chon)
Niece/Nephew: 3 chon (sam chon)
Aunts/Uncles: 3 chon (sam chon)
Cousins: 4 chon (sah chon)
Cousins’ Children: 5 chon (oh chon)
Second Cousins: 6 chon (yuk chon)
A Diagram of Chonsu by the Korean Ministry of Education