first-degree
/ˈfɜːstdɪˈgriː/adjective
attrib.
1
- Medicine denoting burns that affect only the surface of the skin and cause reddening【医】（烧伤）最轻度的, （第）一度的。
2
- Law, chiefly N. Amer. denoting the most serious category of a crime, especially murder【律】〈主北美〉（罪行, 尤指谋杀罪）一级的, 一等的, 最严重的。
短语
first-degree relative
- a person's parent, sibling, or child一等亲属（指某人的父母、同胞兄弟姐妹和子女）。