second-degree relative
Legal and genealogical term for relatives two steps away in the family tree, such as grandparents, grandchildren, and siblings.
Under civil law, second-degree relatives include siblings and grandparents.
親等 is the general term for 'degree of kinship'; 二等親 specifies the second degree.
Standard kanji spelling for 'second-degree relative'.
Variant using numeral ２; less common but seen in some legal or formal contexts.
Compound of 二 (two), 等 (grade/degree), and 親 (relative). The term follows the legal kinship degree system used in Japanese civil law.