quinary
/ˈkwaɪnərɪ/adjective
1- of or relating to the number five, in particular五的, 尤指：
1.1
- of the fifth order or rank第五的。
1.2
- Zoology, historical relating to or denoting a former system of classification in which the animal kingdom is divided into five subkingdoms, and each subkingdom into five classes【动】〈史〉（动物界分类）五分体系的。
词源
early 17th cent.: from Latin quinarius, from quini 'five at once， a set of five'， from quinque 'five'.